[PATCH] Kill PF_SYNCWRITE flag

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

View file

@ -331,7 +331,6 @@ long do_fsync(struct file *file, int datasync)
goto out;
}
current->flags |= PF_SYNCWRITE;
ret = filemap_fdatawrite(mapping);
/*
@ -346,7 +345,6 @@ long do_fsync(struct file *file, int datasync)
err = filemap_fdatawait(mapping);
if (!ret)
ret = err;
current->flags &= ~PF_SYNCWRITE;
out:
return ret;
}