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[PATCH] Kill PF_SYNCWRITE flag

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A process flag to indicate whether we are doing sync io is incredibly
ugly. It also causes performance problems when one does a lot of async
io and then proceeds to sync it. Part of the io will go out as async,
and the other part as sync. This causes a disconnect between the
previously submitted io and the synced io. For io schedulers such as CFQ,
this will cause us lost merges and suboptimal behaviour in scheduling.

Remove PF_SYNCWRITE completely from the fsync/msync paths, and let
the O_DIRECT path just directly indicate that the writes are sync
by using WRITE_SYNC instead.

Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe
2006-06-13 08:26:10 +02:00
committed by Jens Axboe
parent 271f18f102
commit b31dc66a54
10 changed files with 20 additions and 29 deletions
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3
mm/msync.c
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@@ -170,8 +170,6 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
* just ignore them, but return -ENOMEM at the end.
*/
down_read(&current->mm->mmap_sem);
if (flags & MS_SYNC)
current->flags |= PF_SYNCWRITE;
vma = find_vma(current->mm, start);
if (!vma) {
error = -ENOMEM;
@@ -228,7 +226,6 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
}
} while (vma && !done);
out_unlock:
current->flags &= ~PF_SYNCWRITE;
up_read(&current->mm->mmap_sem);
out:
return error;