)]}'
{
  "log": [
    {
      "commit": "11a3122f6cf2d988a77eb8883d0fc49cd013a6d5",
      "tree": "ded8ea8a2982754ff0c58448a7ed2e59487104cb",
      "parents": [
        "822bfa51ce44f2c63c300fdb76dc99c4d5a5ca9f"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Tue Feb 07 07:51:30 2012 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Tue Feb 07 07:51:30 2012 +0100"
      },
      "message": "block: strip out locking optimization in put_io_context()\n\nput_io_context() performed a complex trylock dancing to avoid\ndeferring ioc release to workqueue.  It was also broken on UP because\ntrylock was always assumed to succeed which resulted in unbalanced\npreemption count.\n\nWhile there are ways to fix the UP breakage, even the most\npathological microbench (forced ioc allocation and tight fork/exit\nloop) fails to show any appreciable performance benefit of the\noptimization.  Strip it out.  If there turns out to be workloads which\nare affected by this change, simpler optimization from the discussion\nthread can be applied later.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nLKML-Reference: \u003c1328514611.21268.66.camel@sli10-conroe\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "f1f8cc94651738b418ba54c039df536303b91704",
      "tree": "eb8bc5a33dec104ab32a935a5bb1e1da2e7cdd34",
      "parents": [
        "9b84cacd013996f244d85b3d873287c2a8f88658"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:42 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:42 2011 +0100"
      },
      "message": "block, cfq: move icq creation and rq-\u003eelv.icq association to block core\n\nNow block layer knows everything necessary to create and associate\nicq\u0027s with requests.  Move ioc_create_icq() to blk-ioc.c and update\nget_request() such that, if elevator_type-\u003eicq_size is set, requests\nare automatically associated with their matching icq\u0027s before\nelv_set_request().  io_context reference is also managed by block core\non request alloc/free.\n\n* Only ioprio/cgroup changed handling remains from cfq_get_cic().\n  Collapsed into cfq_set_request().\n\n* This removes queue kicking on icq allocation failure (for now).  As\n  icq allocation failure is rare and the only effect of queue kicking\n  achieved was possibily accelerating queue processing, this change\n  shouldn\u0027t be noticeable.\n\n  There is a larger underlying problem.  Unlike request allocation,\n  icq allocation is not guaranteed to succeed eventually after\n  retries.  The number of icq is unbound and thus mempool can\u0027t be the\n  solution either.  This effectively adds allocation dependency on\n  memory free path and thus possibility of deadlock.\n\n  This usually wouldn\u0027t happen because icq allocation is not a hot\n  path and, even when the condition triggers, it\u0027s highly unlikely\n  that none of the writeback workers already has icq.\n\n  However, this is still possible especially if elevator is being\n  switched under high memory pressure, so we better get it fixed.\n  Probably the only solution is just bypassing elevator and appending\n  to dispatch queue on any elevator allocation failure.\n\n* Comment added to explain how icq\u0027s are managed and synchronized.\n\nThis completes cleanup of io_context interface.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "7e5a8794492e43e9eebb68a98a23be055888ccd0",
      "tree": "cc049a23b2c994f910d3101860bc1c2ecb7aa35f",
      "parents": [
        "3d3c2379feb177a5fd55bb0ed76776dc9d4f3243"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:42 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:42 2011 +0100"
      },
      "message": "block, cfq: move io_cq exit/release to blk-ioc.c\n\nWith kmem_cache managed by blk-ioc, io_cq exit/release can be moved to\nblk-ioc too.  The odd -\u003eio_cq-\u003eexit/release() callbacks are replaced\nwith elevator_ops-\u003eelevator_exit_icq_fn() with unlinking from both ioc\nand q, and freeing automatically handled by blk-ioc.  The elevator\noperation only need to perform exit operation specific to the elevator\n- in cfq\u0027s case, exiting the cfqq\u0027s.\n\nAlso, clearing of io_cq\u0027s on q detach is moved to block core and\nautomatically performed on elevator switch and q release.\n\nBecause the q io_cq points to might be freed before RCU callback for\nthe io_cq runs, blk-ioc code should remember to which cache the io_cq\nneeds to be freed when the io_cq is released.  New field\nio_cq-\u003e__rcu_icq_cache is added for this purpose.  As both the new\nfield and rcu_head are used only after io_cq is released and the\nq/ioc_node fields aren\u0027t, they are put into unions.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "c58698073218f2c8f2fc5982fa3938c2d3803b9f",
      "tree": "ccd2403fd8674051a062efd2c22e6fdd179b7b8f",
      "parents": [
        "22f746e235a5cbee2a6ca9887b1be2aa7d31fe71"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:41 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:41 2011 +0100"
      },
      "message": "block, cfq: reorganize cfq_io_context into generic and cfq specific parts\n\nCurrently io_context and cfq logics are mixed without clear boundary.\nMost of io_context is independent from cfq but cfq_io_context handling\nlogic is dispersed between generic ioc code and cfq.\n\ncfq_io_context represents association between an io_context and a\nrequest_queue, which is a concept useful outside of cfq, but it also\ncontains fields which are useful only to cfq.\n\nThis patch takes out generic part and put it into io_cq (io\ncontext-queue) and the rest into cfq_io_cq (cic moniker remains the\nsame) which contains io_cq.  The following changes are made together.\n\n* cfq_ttime and cfq_io_cq now live in cfq-iosched.c.\n\n* All related fields, functions and constants are renamed accordingly.\n\n* ioc-\u003eioc_data is now \"struct io_cq *\" instead of \"void *\" and\n  renamed to icq_hint.\n\nThis prepares for io_context API cleanup.  Documentation is currently\nsparse.  It will be added later.\n\nChanges in this patch are mechanical and don\u0027t cause functional\nchange.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "1238033c79e92e5c315af12e45396f1a78c73dec",
      "tree": "0f205155f811930f0cf43716e56fa57ea1f792b9",
      "parents": [
        "b50b636bce6293fa858cc7ff6c3ffe4920d90006"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:40 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:40 2011 +0100"
      },
      "message": "block, cfq: kill cic-\u003ekey\n\nNow that lazy paths are removed, cfqd_dead_key() is meaningless and\ncic-\u003eq can be used whereever cic-\u003ekey is used.  Kill cic-\u003ekey.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "b2efa05265d62bc29f3a64400fad4b44340eedb8",
      "tree": "4555f0b5f0025c099997b81f7b3f8bc48b44220d",
      "parents": [
        "f1a4f4d35ff30a328d5ea28f6cc826b2083111d2"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:39 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:39 2011 +0100"
      },
      "message": "block, cfq: unlink cfq_io_context\u0027s immediately\n\ncic is association between io_context and request_queue.  A cic is\nlinked from both ioc and q and should be destroyed when either one\ngoes away.  As ioc and q both have their own locks, locking becomes a\nbit complex - both orders work for removal from one but not from the\nother.\n\nCurrently, cfq tries to circumvent this locking order issue with RCU.\nioc-\u003elock nests inside queue_lock but the radix tree and cic\u0027s are\nalso protected by RCU allowing either side to walk their lists without\ngrabbing lock.\n\nThis rather unconventional use of RCU quickly devolves into extremely\nfragile convolution.  e.g. The following is from cfqd going away too\nsoon after ioc and q exits raced.\n\n general protection fault: 0000 [#1] PREEMPT SMP\n CPU 2\n Modules linked in:\n [   88.503444]\n Pid: 599, comm: hexdump Not tainted 3.1.0-rc10-work+ #158 Bochs Bochs\n RIP: 0010:[\u003cffffffff81397628\u003e]  [\u003cffffffff81397628\u003e] cfq_exit_single_io_context+0x58/0xf0\n ...\n Call Trace:\n  [\u003cffffffff81395a4a\u003e] call_for_each_cic+0x5a/0x90\n  [\u003cffffffff81395ab5\u003e] cfq_exit_io_context+0x15/0x20\n  [\u003cffffffff81389130\u003e] exit_io_context+0x100/0x140\n  [\u003cffffffff81098a29\u003e] do_exit+0x579/0x850\n  [\u003cffffffff81098d5b\u003e] do_group_exit+0x5b/0xd0\n  [\u003cffffffff81098de7\u003e] sys_exit_group+0x17/0x20\n  [\u003cffffffff81b02f2b\u003e] system_call_fastpath+0x16/0x1b\n\nThe only real hot path here is cic lookup during request\ninitialization and avoiding extra locking requires very confined use\nof RCU.  This patch makes cic removal from both ioc and request_queue\nperform double-locking and unlink immediately.\n\n* From q side, the change is almost trivial as ioc-\u003elock nests inside\n  queue_lock.  It just needs to grab each ioc-\u003elock as it walks\n  cic_list and unlink it.\n\n* From ioc side, it\u0027s a bit more difficult because of inversed lock\n  order.  ioc needs its lock to walk its cic_list but can\u0027t grab the\n  matching queue_lock and needs to perform unlock-relock dancing.\n\n  Unlinking is now wholly done from put_io_context() and fast path is\n  optimized by using the queue_lock the caller already holds, which is\n  by far the most common case.  If the ioc accessed multiple devices,\n  it tries with trylock.  In unlikely cases of fast path failure, it\n  falls back to full double-locking dance from workqueue.\n\nDouble-locking isn\u0027t the prettiest thing in the world but it\u0027s *far*\nsimpler and more understandable than RCU trick without adding any\nmeaningful overhead.\n\nThis still leaves a lot of now unnecessary RCU logics.  Future patches\nwill trim them.\n\n-v2: Vivek pointed out that cic-\u003eq was being dereferenced after\n     cic-\u003erelease() was called.  Updated to use local variable @this_q\n     instead.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nCc: Vivek Goyal \u003cvgoyal@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "dc86900e0a8f665122de6faadd27fb4c6d2b3e4d",
      "tree": "ec24aa4b076f54fcfb0558d5113f5c5e0f4bc173",
      "parents": [
        "283287a52e3c3f7f8f9da747f4b8c5202740d776"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "message": "block, cfq: move ioc ioprio/cgroup changed handling to cic\n\nioprio/cgroup change was handled by marking the changed state in ioc\nand, on the following access to the ioc, performing RCU-protected\niteration through all cic\u0027s grabbing the matching queue_lock.\n\nThis patch moves the changed state to each cic.  When ioprio or cgroup\nchanges, the respective bit is set on all cic\u0027s of the ioc and when\neach of those cic (not ioc) is accessed, change is applied for that\nspecific ioc-queue pair.\n\nThis also fixes the following two race conditions between setting and\nclearing of changed states.\n\n* Missing barrier between assign/load of ioprio and ioprio_changed\n  allowed applying old ioprio.\n\n* Change requests could happen between application of change and\n  clearing of changed variables.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "283287a52e3c3f7f8f9da747f4b8c5202740d776",
      "tree": "b5b145bcdcefc24deb68cd91bb16582286dce171",
      "parents": [
        "09ac46c429464c919d04bb737b27edd84d944f02"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "message": "block, cfq: misc updates to cfq_io_context\n\nMake the following changes to prepare for ioc/cic management cleanup.\n\n* Add cic-\u003eq so that ioc can determine the associated queue without\n  querying cfq.  This will eventually replace -\u003ekey.\n\n* Factor out cfq_release_cic() from cic_free_func().  This function\n  assumes that the caller handled locking.\n\n* Rename __cfq_exit_single_io_context() to cfq_exit_cic() and make it\n  take only @cic.\n\n* Restructure cfq_cic_link() for future updates.\n\nThis patch doesn\u0027t introduce any functional changes.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "6e736be7f282fff705db7c34a15313281b372a76",
      "tree": "1683e00e073ee4bd3027798f92ae2d368404d44b",
      "parents": [
        "42ec57a8f68311bbbf4ff96a5d33c8a2e90b9d05"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:38 2011 +0100"
      },
      "message": "block: make ioc get/put interface more conventional and fix race on alloction\n\nIgnoring copy_io() during fork, io_context can be allocated from two\nplaces - current_io_context() and set_task_ioprio().  The former is\nalways called from local task while the latter can be called from\ndifferent task.  The synchornization between them are peculiar and\ndubious.\n\n* current_io_context() doesn\u0027t grab task_lock() and assumes that if it\n  saw %NULL -\u003eio_context, it would stay that way until allocation and\n  assignment is complete.  It has smp_wmb() between alloc/init and\n  assignment.\n\n* set_task_ioprio() grabs task_lock() for assignment and does\n  smp_read_barrier_depends() between \"ioc \u003d task-\u003eio_context\" and \"if\n  (ioc)\".  Unfortunately, this doesn\u0027t achieve anything - the latter\n  is not a dependent load of the former.  ie, if ioc itself were being\n  dereferenced \"ioc-\u003exxx\", it would mean something (not sure what tho)\n  but as the code currently stands, the dependent read barrier is\n  noop.\n\nAs only one of the the two test-assignment sequences is task_lock()\nprotected, the task_lock() can\u0027t do much about race between the two.\nNothing prevents current_io_context() and set_task_ioprio() allocating\nits own ioc for the same task and overwriting the other\u0027s.\n\nAlso, set_task_ioprio() can race with exiting task and create a new\nioc after exit_io_context() is finished.\n\nioc get/put doesn\u0027t have any reason to be complex.  The only hot path\nis accessing the existing ioc of %current, which is simple to achieve\ngiven that -\u003eio_context is never destroyed as long as the task is\nalive.  All other paths can happily go through task_lock() like all\nother task sub structures without impacting anything.\n\nThis patch updates ioc get/put so that it becomes more conventional.\n\n* alloc_io_context() is replaced with get_task_io_context().  This is\n  the only interface which can acquire access to ioc of another task.\n  On return, the caller has an explicit reference to the object which\n  should be put using put_io_context() afterwards.\n\n* The functionality of current_io_context() remains the same but when\n  creating a new ioc, it shares the code path with\n  get_task_io_context() and always goes through task_lock().\n\n* get_io_context() now means incrementing ref on an ioc which the\n  caller already has access to (be that an explicit refcnt or implicit\n  %current one).\n\n* PF_EXITING inhibits creation of new io_context and once\n  exit_io_context() is finished, it\u0027s guaranteed that both ioc\n  acquisition functions return %NULL.\n\n* All users are updated.  Most are trivial but\n  smp_read_barrier_depends() removal from cfq_get_io_context() needs a\n  bit of explanation.  I suppose the original intention was to ensure\n  ioc-\u003eioprio is visible when set_task_ioprio() allocates new\n  io_context and installs it; however, this wouldn\u0027t have worked\n  because set_task_ioprio() doesn\u0027t have wmb between init and install.\n  There are other problems with this which will be fixed in another\n  patch.\n\n* While at it, use NUMA_NO_NODE instead of -1 for wildcard node\n  specification.\n\n-v2: Vivek spotted contamination from debug patch.  Removed.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nCc: Vivek Goyal \u003cvgoyal@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "42ec57a8f68311bbbf4ff96a5d33c8a2e90b9d05",
      "tree": "3aead2658435f53bd637967c5722358039acc390",
      "parents": [
        "a73f730d013ff2788389fd0c46ad3e5510f124e6"
      ],
      "author": {
        "name": "Tejun Heo",
        "email": "tj@kernel.org",
        "time": "Wed Dec 14 00:33:37 2011 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "axboe@kernel.dk",
        "time": "Wed Dec 14 00:33:37 2011 +0100"
      },
      "message": "block: misc ioc cleanups\n\n* int return from put_io_context() wasn\u0027t used by anybody.  Make it\n  return void like other put functions and docbook-fy the function\n  comment.\n\n* Reorder dummy declarations for !CONFIG_BLOCK case a bit.\n\n* Make alloc_ioc_context() use __GFP_ZERO allocation, take init out of\n  if block and drop 0\u0027ing.\n\n* Docbook-fy current_io_context() comment.\n\nThis patch doesn\u0027t introduce any functional change.\n\nSigned-off-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Jens Axboe \u003caxboe@kernel.dk\u003e\n"
    },
    {
      "commit": "383cd7213f95a2784ab5038fe292844178768b82",
      "tree": "625de0648246daff30a9030e350c29584d29441e",
      "parents": [
        "4aede84b33d6beb401136a3deca0651ae07c5e99"
      ],
      "author": {
        "name": "Shaohua Li",
        "email": "shaohua.li@intel.com",
        "time": "Tue Jul 12 14:24:35 2011 +0200"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jaxboe@fusionio.com",
        "time": "Tue Jul 12 14:24:35 2011 +0200"
      },
      "message": "CFQ: move think time check variables to a separate struct\n\nMove the variables to do think time check to a sepatate struct. This is\nto prepare adding think time check for service tree and group. No\nfunctional change.\n\nSigned-off-by: Shaohua Li \u003cshaohua.li@intel.com\u003e\nAcked-by: Vivek Goyal \u003cvgoyal@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003cjaxboe@fusionio.com\u003e\n"
    },
    {
      "commit": "cedb4a7d9f6aedb0dce94d6285b69dcb3c10fa05",
      "tree": "49a6b255a727421658cb917321ad3e29c8bd9fc0",
      "parents": [
        "17a9e7bbae178d1326e4631ab6350a272349c99d"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jaxboe@fusionio.com",
        "time": "Thu Nov 11 13:37:54 2010 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jaxboe@fusionio.com",
        "time": "Thu Nov 11 13:40:11 2010 +0100"
      },
      "message": "block: remove unused copy_io_context()\n\nReported-by: Oleg Nesterov \u003coleg@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003cjaxboe@fusionio.com\u003e\n"
    },
    {
      "commit": "4d2deb40b20c2608486598364e63e37b09a9ac2f",
      "tree": "cf61f5492623fa69ddc9a0573b50d52b002c2f85",
      "parents": [
        "d2c2486bc8e185548490e8edbc84d185de9eaff1"
      ],
      "author": {
        "name": "Arnd Bergmann",
        "email": "arnd@arndb.de",
        "time": "Wed Feb 24 20:01:56 2010 +0100"
      },
      "committer": {
        "name": "Paul E. McKenney",
        "email": "paulmck@linux.vnet.ibm.com",
        "time": "Thu Aug 19 17:18:03 2010 -0700"
      },
      "message": "kernel: __rcu annotations\n\nThis adds annotations for RCU operations in core kernel components\n\nSigned-off-by: Arnd Bergmann \u003carnd@arndb.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: Al Viro \u003cviro@ZenIV.linux.org.uk\u003e\nCc: Jens Axboe \u003cjens.axboe@oracle.com\u003e\nCc: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n"
    },
    {
      "commit": "bca4b914b5da3d8e7b9b647f620b71dc85c0c394",
      "tree": "ed9c468396ec6ca6a04da9f7fbc341eee95e3930",
      "parents": [
        "f4b87dee923342505e1ddba8d34ce9de33e75050"
      ],
      "author": {
        "name": "Konstantin Khlebnikov",
        "email": "khlebnikov@openvz.org",
        "time": "Thu May 20 23:21:34 2010 +0400"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon May 24 09:06:59 2010 +0200"
      },
      "message": "cfq-iosched: remove dead_key from cfq_io_context\n\nRemove -\u003edead_key field from cfq_io_context to shrink its size to 128 bytes.\n(64 bytes for 32-bit hosts)\n\nUse lower bit in -\u003ekey as dead-mark, instead of moving key to separate field.\nAfter this for dead cfq_io_context we got cic-\u003ekey !\u003d cfqd automatically.\nThus, io_context\u0027s last-hit cache should work without changing.\n\nNow to check -\u003ekey for non-dead state compare it with cfqd,\ninstead of checking -\u003ekey for non-null value as it was before.\n\nPlus remove obsolete race protection in cfq_cic_lookup.\nThis race gone after v2.6.24-1728-g4ac845a\n\nSigned-off-by: Konstantin Khlebnikov \u003ckhlebnikov@openvz.org\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "67523c48aa74d5637848edeccf285af1c60bf14a",
      "tree": "ebd14992e210c8dfb503ae5fdffc1f5392ad52df",
      "parents": [
        "8ca712ea84728531d36841ca8f98f9e8680bcf4e"
      ],
      "author": {
        "name": "Ben Blum",
        "email": "bblum@andrew.cmu.edu",
        "time": "Wed Mar 10 15:22:11 2010 -0800"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Fri Mar 12 15:52:36 2010 -0800"
      },
      "message": "cgroups: blkio subsystem as module\n\nModify the Block I/O cgroup subsystem to be able to be built as a module.\nAs the CFQ disk scheduler optionally depends on blk-cgroup, config options\nin block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are\nenhanced to support the new module dependency.\n\nSigned-off-by: Ben Blum \u003cbblum@andrew.cmu.edu\u003e\nCc: Li Zefan \u003clizf@cn.fujitsu.com\u003e\nCc: Paul Menage \u003cmenage@google.com\u003e\nCc: \"David S. Miller\" \u003cdavem@davemloft.net\u003e\nCc: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nCc: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nCc: Vivek Goyal \u003cvgoyal@redhat.com\u003e\nCc: Jens Axboe \u003cjens.axboe@oracle.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "58c24a61614f5da290068e47fc5ec65370eb61dd",
      "tree": "ae8f51cef37239a4ebe12379deca7042680161c1",
      "parents": [
        "024f9066165ffe9c8284431c78adcbcddd309831"
      ],
      "author": {
        "name": "Richard Kennedy",
        "email": "richard@rsk.demon.co.uk",
        "time": "Fri Feb 26 14:00:43 2010 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Fri Feb 26 14:00:43 2010 +0100"
      },
      "message": "block: remove padding from io_context on 64bit builds\n\nOn 64 bit builds when CONFIG_BLK_CGROUP\u003dn (the default) this removes 8\nbytes of padding from structure io_context and drops its size from 72 to\n64 bytes, so needing one fewer cachelines and allowing more objects per\nslab in it\u0027s kmem_cache.\n\nSigned-off-by: Richard Kennedy \u003crichard@rsk.demon.co.uk\u003e\n\n----\npatch against 2.6.33\ncompiled \u0026 test on x86_64 AMDX2\nregards\nRichard\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "ce289321b7dc1eb108e3df0dec872b7429ef49f7",
      "tree": "9153bc19d805d796b7a9ddac04d2d060a9d3261e",
      "parents": [
        "b27d7f16d3c6c27345d4280a739809c1c2c4c0b5"
      ],
      "author": {
        "name": "Kirill Afonshin",
        "email": "kirill_nnov@mail.ru",
        "time": "Fri Jan 08 22:09:59 2010 +0300"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Jan 11 14:29:20 2010 +0100"
      },
      "message": "block: removed unused as_io_context\n\nIt isn\u0027t used anymore, since AS was deleted.\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "b69f2292063d2caf37ca9aec7d63ded203701bf3",
      "tree": "be4acb81ea4ab7014047808ec2b2c908e8334f55",
      "parents": [
        "61cc74fbb87af6aa551a06a370590c9bc07e29d9"
      ],
      "author": {
        "name": "Louis Rilling",
        "email": "louis.rilling@kerlabs.com",
        "time": "Fri Dec 04 14:52:42 2009 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Fri Dec 04 16:36:18 2009 +0100"
      },
      "message": "block: Fix io_context leak after failure of clone with CLONE_IO\n\nWith CLONE_IO, parent\u0027s io_context-\u003enr_tasks is incremented, but never\ndecremented whenever copy_process() fails afterwards, which prevents\nexit_io_context() from calling IO schedulers exit functions.\n\nGive a task_struct to exit_io_context(), and call exit_io_context() instead of\nput_io_context() in copy_process() cleanup path.\n\nSigned-off-by: Louis Rilling \u003clouis.rilling@kerlabs.com\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "31e4c28d95e64f2d5d3c497a3ecf37c62de635b4",
      "tree": "ffbb99b2565c4bdd4921fd7077164e7fc295b2bc",
      "parents": [
        "1fa8f6d68b5c8ca0a608fd8d296c5f07ac788cd6"
      ],
      "author": {
        "name": "Vivek Goyal",
        "email": "vgoyal@redhat.com",
        "time": "Thu Dec 03 12:59:42 2009 -0500"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Thu Dec 03 19:28:51 2009 +0100"
      },
      "message": "blkio: Introduce blkio controller cgroup interface\n\no This is basic implementation of blkio controller cgroup interface. This is\n  the common interface visible to user space and should be used by different\n  IO control policies as we implement those.\n\nSigned-off-by: Vivek Goyal \u003cvgoyal@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "b2c18e1e08a5a9663094d57bb4be2f02226ee61c",
      "tree": "55c092706a0d8a9e645f245bf2ecc45c29ba5aa7",
      "parents": [
        "c30f33437c3f85ec48353a1ef811e148217a2aaf"
      ],
      "author": {
        "name": "Jeff Moyer",
        "email": "jmoyer@redhat.com",
        "time": "Fri Oct 23 17:14:49 2009 -0400"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Oct 26 14:34:46 2009 +0100"
      },
      "message": "cfq: calculate the seek_mean per cfq_queue not per cfq_io_context\n\nasync cfq_queue\u0027s are already shared between processes within the same\npriority, and forthcoming patches will change the mapping of cic to sync\ncfq_queue from 1:1 to 1:N.  So, calculate the seekiness of a process\nbased on the cfq_queue instead of the cfq_io_context.\n\nSigned-off-by: Jeff Moyer \u003cjmoyer@redhat.com\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "cbb4f2646d77b536ed2b1500ef6641083228ed8f",
      "tree": "e238098c2239ca1a2ec978858f63566d0281d49a",
      "parents": [
        "56ad1740d9a8dc271e71fee234be662638c64458"
      ],
      "author": {
        "name": "Li Zefan",
        "email": "lizf@cn.fujitsu.com",
        "time": "Fri Jul 31 08:55:48 2009 +0200"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Fri Jul 31 08:55:48 2009 +0200"
      },
      "message": "io context: fix ref counting\n\nCommit d9c7d394a8ebacb60097b192939ae9f15235225e\n(\"block: prevent possible io_context-\u003erefcount overflow\") mistakenly\nchanged atomic_inc(\u0026ioc-\u003enr_tasks) to atomic_long_inc(\u0026ioc-\u003erefcount).\n\nSigned-off-by: Li Zefan \u003clizf@cn.fujitsu.com\u003e\nAcked-by: Nikanth Karthikesan \u003cknikanth@suse.de\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "d9c7d394a8ebacb60097b192939ae9f15235225e",
      "tree": "4fbf9c7677acb03c23d05faba1a4b0bcfb6702b4",
      "parents": [
        "1d589bb16b825b3a7b4edd34d997f1f1f953033d"
      ],
      "author": {
        "name": "Nikanth Karthikesan",
        "email": "knikanth@novell.com",
        "time": "Wed Jun 10 12:57:06 2009 -0700"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Wed Jun 10 23:07:15 2009 +0200"
      },
      "message": "block: prevent possible io_context-\u003erefcount overflow\n\nCurrently io_context has an atomic_t(32-bit) as refcount.  In the case of\ncfq, for each device against whcih a task does I/O, a reference to the\nio_context would be taken.  And when there are multiple process sharing\nio_contexts(CLONE_IO) would also have a reference to the same io_context.\n\nTheoretically the possible maximum number of processes sharing the same\nio_context + the number of disks/cfq_data referring to the same io_context\ncan overflow the 32-bit counter on a very high-end machine.\n\nEven though it is an improbable case, let us make it atomic_long_t.\n\nSigned-off-by: Nikanth Karthikesan \u003cknikanth@suse.de\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "da9cbc87395308a21465bd25441297bbba0477e1",
      "tree": "fabea3326cea434c0011fa00f3eb57854162117c",
      "parents": [
        "b984679efe1a616ec4ac919dba08286d71593900"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Jun 30 20:42:08 2008 +0200"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Thu Jul 03 13:21:14 2008 +0200"
      },
      "message": "block: blkdev.h cleanup, move iocontext stuff to iocontext.h\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "d237e5c7ce82b6c7e1aa50348520a0c5a47274fa",
      "tree": "7ba37198dea89e4168cb660175057058ebbf11f1",
      "parents": [
        "a985aabe4d7a720b109c2b63549f8641676a9c88"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Tue Apr 15 09:25:33 2008 +0200"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Tue Apr 15 09:25:33 2008 +0200"
      },
      "message": "io context: increment task attachment count in ioc_task_link()\n\nThanks to Nikanth Karthikesan \u003cknikanth@suse.de\u003e for reporting this.\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "34e6bbf23c8f43e8713d9bd092680f1660494b4a",
      "tree": "908e97ac3d43882cb42bf57c41926852d3bc2f6e",
      "parents": [
        "00d61e3e8c12d5f395b167856d2b3c430816afb0"
      ],
      "author": {
        "name": "Fabio Checconi",
        "email": "fabio@gandalf.sssup.i",
        "time": "Wed Apr 02 14:31:02 2008 +0200"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Wed Apr 02 15:42:20 2008 +0200"
      },
      "message": "cfq-iosched: fix rcu freeing of cfq io contexts\n\nSLAB_DESTROY_BY_RCU is not a direct substitute for normal call_rcu()\nfreeing, since it\u0027ll page freeing but NOT object freeing. So change\ncfq to do the freeing on its own.\n\nSigned-off-by: Fabio Checconi \u003cfabio@gandalf.sssup.it\u003e\nAcked-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "ffc4e7595734cf768fa60cea8a4d545dfef8231a",
      "tree": "9b95aca67ea7c9e87254da501f73cca64504051d",
      "parents": [
        "84e9e03c55c2456799ab19f1d577e72f721fdd39"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Tue Feb 19 10:02:29 2008 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Tue Feb 19 10:04:00 2008 +0100"
      },
      "message": "cfq-iosched: add hlist for browsing parallel to the radix tree\n\nIt\u0027s cumbersome to browse a radix tree from start to finish, especially\nsince we modify keys when a process exits. So add a hlist for the single\npurpose of browsing over all known cfq_io_contexts, used for exit,\nio prio change, etc.\n\nThis fixes http://bugzilla.kernel.org/show_bug.cgi?id\u003d9948\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "4ac845a2e9a816ed5a7b301f56dcc0a3d0b1ba4d",
      "tree": "602f15808d0f3dcdfcd7cc4491b2cc2ccd266fd2",
      "parents": [
        "66dac98ed0de7a1125fb0dd7907f238f6b9d2f60"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Thu Jan 24 08:44:49 2008 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Jan 28 10:50:33 2008 +0100"
      },
      "message": "block: cfq: make the io contect sharing lockless\n\nThe io context sharing introduced a per-ioc spinlock, that would protect\nthe cfq io context lookup. That is a regression from the original, since\nwe never needed any locking there because the ioc/cic were process private.\n\nThe cic lookup is changed from an rbtree construct to a radix tree, which\nwe can then use RCU to make the reader side lockless. That is the performance\ncritical path, modifying the radix tree is only done on process creation\n(when that process first does IO, actually) and on process exit (if that\nprocess has done IO).\n\nAs it so happens, radix trees are also much faster for this type of\nlookup where the key is a pointer. It\u0027s a very sparse tree.\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "d38ecf935fcb10264a6bc190855d9595165e6eeb",
      "tree": "64e3146ef76678ad3ae8f75c32df9f25ea470953",
      "parents": [
        "fd0928df98b9578be8a786ac0cb78a47a5e17a20"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Thu Jan 24 08:53:35 2008 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Jan 28 10:50:31 2008 +0100"
      },
      "message": "io context sharing: preliminary support\n\nDetach task state from ioc, instead keep track of how many processes\nare accessing the ioc.\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    },
    {
      "commit": "fd0928df98b9578be8a786ac0cb78a47a5e17a20",
      "tree": "70a34cf207bea1bec28e59cf0dba7d20e7f8b0f1",
      "parents": [
        "91525300baf162e83e923b09ca286f9205e21522"
      ],
      "author": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Thu Jan 24 08:52:45 2008 +0100"
      },
      "committer": {
        "name": "Jens Axboe",
        "email": "jens.axboe@oracle.com",
        "time": "Mon Jan 28 10:50:29 2008 +0100"
      },
      "message": "ioprio: move io priority from task_struct to io_context\n\nThis is where it belongs and then it doesn\u0027t take up space for a\nprocess that doesn\u0027t do IO.\n\nSigned-off-by: Jens Axboe \u003cjens.axboe@oracle.com\u003e\n"
    }
  ]
}