The patch titled sys_sync(): fix 16% performance regression in ffsb create_4k test has been removed from the -mm tree. Its filename was sys_sync-fix-16%-performance-regression-in-ffsb-create_4k-test.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: sys_sync(): fix 16% performance regression in ffsb create_4k test From: "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx> I run many ffsb test cases on JBODs (typically 13/12 disks). Comparing with kernel 2.6.30, 2.6.31-rc1 has about 16% regression with ffsb_create_4k. The sub test case creates files continuously for 10 minitues and every file is 1MB. Bisect located below patch. 5cee5815d1564bbbd505fea86f4550f1efdb5cd0 is first bad commit commit 5cee5815d1564bbbd505fea86f4550f1efdb5cd0 Author: Jan Kara <jack@xxxxxxx> Date: Mon Apr 27 16:43:51 2009 +0200 vfs: Make sys_sync() use fsync_super() (version 4) It is unnecessarily fragile to have two places (fsync_super() and do_sync()) doing data integrity sync of the filesystem. Alter __fsync_super() to accommodate needs of both callers and use it. So after this patch __fsync_super() is the only place where we gather all the calls needed to properly send all data on a filesystem to disk. As a matter of fact, ffsb calls sys_sync in the end to make sure all data is flushed to disks and the flushing is counted into the result. vmstat shows ffsb is blocked when syncing for a long time. With 2.6.30, ffsb is blocked for a short time. I checked the patch and did experiments to recover the original methods. Eventually, the root cause is the patch deletes the calling to wakeup_pdflush when syncing, so only ffsb is blocked on disk I/O. wakeup_pdflush could ask pdflush to write back pages with ffsb at the same time. [akpm@xxxxxxxxxxxxxxxxxxxx: restore comment too] Signed-off-by: Zhang Yanmin <yanmin_zhang@xxxxxxxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Acked-by: Jens Axboe <jens.axboe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/sync.c | 5 +++++ 1 file changed, 5 insertions(+) diff -puN fs/sync.c~sys_sync-fix-16%-performance-regression-in-ffsb-create_4k-test fs/sync.c --- a/fs/sync.c~sys_sync-fix-16%-performance-regression-in-ffsb-create_4k-test +++ a/fs/sync.c @@ -112,8 +112,13 @@ restart: mutex_unlock(&mutex); } +/* + * sync everything. Start out by waking pdflush, because that writes back + * all queues in parallel. + */ SYSCALL_DEFINE0(sync) { + wakeup_pdflush(0); sync_filesystems(0); sync_filesystems(1); if (unlikely(laptop_mode)) _ Patches currently in -mm which might be from yanmin_zhang@xxxxxxxxxxxxxxx are kernel-core-add-smp_call_function_any.patch kernel-core-add-smp_call_function_any-update.patch arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-cross-cpu-interrupts-by-using-smp_call_function_any.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html