From b31dc66a54ad986b6b73bdc49c8efc17cbad1833 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 13 Jun 2006 08:26:10 +0200 Subject: [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 --- block/cfq-iosched.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index c88f161d3fb3..4c4e9cc3ae26 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -277,8 +277,6 @@ static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsi static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); -#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) - /* * lots of deadline iosched dupes, can be abstracted later... */ @@ -334,7 +332,7 @@ static int cfq_queue_empty(request_queue_t *q) static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) { - if (rw == READ || process_sync(task)) + if (rw == READ || rw == WRITE_SYNC) return task->pid; return CFQ_KEY_ASYNC; -- cgit v1.2.3