jbd2: add tracepoints which provide per-handle statistics
Handles which stay open a long time are problematic when it comes time
to close down a transaction so it can be committed. These tracepoints
will help us determine which ones are the problematic ones, and to
validate whether changes makes things better or worse.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 735609e..b7e2385 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -30,6 +30,8 @@
#include <linux/bug.h>
#include <linux/module.h>
+#include <trace/events/jbd2.h>
+
static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
@@ -307,6 +309,8 @@
*/
update_t_max_wait(transaction, ts);
handle->h_transaction = transaction;
+ handle->h_requested_credits = nblocks;
+ handle->h_start_jiffies = jiffies;
atomic_inc(&transaction->t_updates);
atomic_inc(&transaction->t_handle_count);
jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
@@ -353,7 +357,8 @@
* Return a pointer to a newly allocated handle, or an ERR_PTR() value
* on failure.
*/
-handle_t *jbd2__journal_start(journal_t *journal, int nblocks, gfp_t gfp_mask)
+handle_t *jbd2__journal_start(journal_t *journal, int nblocks, gfp_t gfp_mask,
+ unsigned int type, unsigned int line_no)
{
handle_t *handle = journal_current_handle();
int err;
@@ -379,6 +384,11 @@
current->journal_info = NULL;
handle = ERR_PTR(err);
}
+ handle->h_type = type;
+ handle->h_line_no = line_no;
+ trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
+ handle->h_transaction->t_tid, type,
+ line_no, nblocks);
return handle;
}
EXPORT_SYMBOL(jbd2__journal_start);
@@ -386,7 +396,7 @@
handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
{
- return jbd2__journal_start(journal, nblocks, GFP_NOFS);
+ return jbd2__journal_start(journal, nblocks, GFP_NOFS, 0, 0);
}
EXPORT_SYMBOL(jbd2_journal_start);
@@ -448,7 +458,14 @@
goto unlock;
}
+ trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
+ handle->h_transaction->t_tid,
+ handle->h_type, handle->h_line_no,
+ handle->h_buffer_credits,
+ nblocks);
+
handle->h_buffer_credits += nblocks;
+ handle->h_requested_credits += nblocks;
atomic_add(nblocks, &transaction->t_outstanding_credits);
result = 0;
@@ -1377,6 +1394,13 @@
}
jbd_debug(4, "Handle %p going down\n", handle);
+ trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
+ handle->h_transaction->t_tid,
+ handle->h_type, handle->h_line_no,
+ jiffies - handle->h_start_jiffies,
+ handle->h_sync, handle->h_requested_credits,
+ (handle->h_requested_credits -
+ handle->h_buffer_credits));
/*
* Implement synchronous transaction batching. If the handle