[PATCH] i386: use thread_info flags for debug regs and IO bitmaps
Use thread info flags to track use of debug registers and IO bitmaps.
- add TIF_DEBUG to track when debug registers are active
- add TIF_IO_BITMAP to track when I/O bitmap is used
- modify __switch_to() to use the new TIF flags
Performance tested on Pentium II, ten runs of LMbench context switch
benchmark (smaller is better:)
before after
avg 3.65 3.39
min 3.55 3.33
Signed-off-by: Stephane Eranian <eranian@hpl.hp.com>
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/ioport.c b/arch/i386/kernel/ioport.c
index 79026f0..498e8bc 100644
--- a/arch/i386/kernel/ioport.c
+++ b/arch/i386/kernel/ioport.c
@@ -79,6 +79,7 @@
memset(bitmap, 0xff, IO_BITMAP_BYTES);
t->io_bitmap_ptr = bitmap;
+ set_thread_flag(TIF_IO_BITMAP);
}
/*