{"push_id":581681621,"size":1,"distinct_size":1,"ref":"refs/heads/cm-12.0_staging","head":"c89e99ede403dab8d4b435ec5964f10ba7c00364","before":"a0d6126b46b6b4fa2854275448dd63097397525b","commits":[{"sha":"c89e99ede403dab8d4b435ec5964f10ba7c00364","author":{"email":"4d9e23a041ac966f5316a7481300d4ae12e806fe@redhat.com","name":"Dave Chinner"},"message":"sync: don't block the flusher thread waiting on IO\n\nWhen sync does it's WB_SYNC_ALL writeback, it issues data Io and\nthen immediately waits for IO completion. This is done in the\ncontext of the flusher thread, and hence completely ties up the\nflusher thread for the backing device until all the dirty inodes\nhave been synced. On filesystems that are dirtying inodes constantly\nand quickly, this means the flusher thread can be tied up for\nminutes per sync call and hence badly affect system level write IO\nperformance as the page cache cannot be cleaned quickly.\n\nWe already have a wait loop for IO completion for sync(2), so cut\nthis out of the flusher thread and delegate it to wait_sb_inodes().\nHence we can do rapid IO submission, and then wait for it all to\ncomplete.\n\nEffect of sync on fsmark before the patch:\n\nFSUse%        Count         Size    Files/sec     App Overhead\n.....\n     0       640000         4096      35154.6          1026984\n     0       720000         4096      36740.3          1023844\n     0       800000         4096      36184.6           916599\n     0       880000         4096       1282.7          1054367\n     0       960000         4096       3951.3           918773\n     0      1040000         4096      40646.2           996448\n     0      1120000         4096      43610.1           895647\n     0      1200000         4096      40333.1           921048\n\nAnd a single sync pass took:\n\n  real    0m52.407s\n  user    0m0.000s\n  sys     0m0.090s\n\nAfter the patch, there is no impact on fsmark results, and each\nindividual sync(2) operation run concurrently with the same fsmark\nworkload takes roughly 7s:\n\n  real    0m6.930s\n  user    0m0.000s\n  sys     0m0.039s\n\nIOWs, sync is 7-8x faster on a busy filesystem and does not have an\nadverse impact on ongoing async data write operations.\n\nSigned-off-by: Dave Chinner <dchinner@redhat.com>\nReviewed-by: Jan Kara <jack@suse.cz>\nSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>\nSigned-off-by: Francisco Franco <franciscofranco.1990@gmail.com>","distinct":true,"url":"https://api.github.com/repos/Starship-Android/android_kernel_lge_hammerhead-starship/commits/c89e99ede403dab8d4b435ec5964f10ba7c00364"}]}