[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>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a9d23c7..38b4791e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -941,12 +941,11 @@
#define PF_KSWAPD 0x00040000 /* I am kswapd */
#define PF_SWAPOFF 0x00080000 /* I am in swapoff */
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
-#define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */
-#define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */
-#define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */
-#define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */
-#define PF_SPREAD_PAGE 0x04000000 /* Spread page cache over cpuset */
-#define PF_SPREAD_SLAB 0x08000000 /* Spread some slab caches over cpuset */
+#define PF_BORROWED_MM 0x00200000 /* I am a kthread doing use_mm */
+#define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */
+#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
+#define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */
+#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
/*