On Fri, Aug 12, 2016 at 11:03:33AM -0700, Linus Torvalds wrote: >On Thu, Aug 11, 2016 at 8:56 PM, Dave Chinner wrote: >> On Thu, Aug 11, 2016 at 07:27:52PM -0700, Linus Torvalds wrote: >>> >>> I don't recall having ever seen the mapping tree_lock as a contention >>> point before, but it's not like I've tried that load either. So it >>> might be a regression (going back long, I suspect), or just an unusual >>> load that nobody has traditionally tested much. >>> >>> Single-threaded big file write one page at a time, was it? >> >> Yup. On a 4 node NUMA system. > >Ok, I can't see any real contention on my single-node workstation >(running ext4 too, so there may be filesystem differences), but I >guess that shouldn't surprise me. The cacheline bouncing just isn't >expensive enough when it all stays on-die. > >I can see the tree_lock in my profiles (just not very high), and at >least for ext4 the main caller ssems to be >__set_page_dirty_nobuffers(). > >And yes, looking at that, the biggest cost by _far_ inside the >spinlock seems to be the accounting. > >Which doesn't even have to be inside the mapping lock, as far as I can >tell, and as far as comments go. > >So a stupid patch to just move the dirty page accounting to outside >the spinlock might help a lot. > >Does this attached patch help your contention numbers? Hi Linus, The 1BRD tests finished and there are no conclusive changes. The overall aim7 jobs-per-min slightly decreases and the overall fsmark files_per_sec slightly increases, however both are small enough (less than 1%), which are kind of expected numbers. NUMA test results should be available tomorrow. 99091700659f4df9 1b5f2eb4a752e1fa7102f37545 testcase/testparams/testbox ---------------- -------------------------- --------------------------- %stddev %change %stddev \ | \ 71443 71286 GEO-MEAN aim7.jobs-per-min 972 961 aim7/1BRD_48G-btrfs-creat-clo-4-performance/ivb44 52205 51525 aim7/1BRD_48G-btrfs-disk_cp-1500-performance/ivb44 2184471 ± 4% -6% 2051740 ± 3% aim7/1BRD_48G-btrfs-disk_rd-9000-performance/ivb44 47049 46630 ± 3% aim7/1BRD_48G-btrfs-disk_rr-1500-performance/ivb44 24932 -4% 23812 aim7/1BRD_48G-btrfs-disk_rw-1500-performance/ivb44 5884 5856 aim7/1BRD_48G-btrfs-disk_src-500-performance/ivb44 51430 51286 aim7/1BRD_48G-btrfs-disk_wrt-1500-performance/ivb44 218 220 aim7/1BRD_48G-btrfs-sync_disk_rw-10-performance/ivb44 22777 23199 aim7/1BRD_48G-ext4-creat-clo-1000-performance/ivb44 130085 128991 aim7/1BRD_48G-ext4-disk_cp-3000-performance/ivb44 2434088 ± 3% -8% 2232211 ± 4% aim7/1BRD_48G-ext4-disk_rd-9000-performance/ivb44 130351 128977 aim7/1BRD_48G-ext4-disk_rr-3000-performance/ivb44 73280 74044 aim7/1BRD_48G-ext4-disk_rw-3000-performance/ivb44 277035 -3% 268057 aim7/1BRD_48G-ext4-disk_src-3000-performance/ivb44 127584 4% 132639 aim7/1BRD_48G-ext4-disk_wrt-3000-performance/ivb44 10571 10659 aim7/1BRD_48G-ext4-sync_disk_rw-600-performance/ivb44 36924 ± 7% 36327 aim7/1BRD_48G-f2fs-creat-clo-1500-performance/ivb44 117238 119130 aim7/1BRD_48G-f2fs-disk_cp-3000-performance/ivb44 2340512 ± 5% 2352619 ± 10% aim7/1BRD_48G-f2fs-disk_rd-9000-performance/ivb44 107506 ± 9% 7% 114869 aim7/1BRD_48G-f2fs-disk_rr-3000-performance/ivb44 105642 106835 aim7/1BRD_48G-f2fs-disk_rw-3000-performance/ivb44 26900 ± 3% 26442 ± 3% aim7/1BRD_48G-f2fs-disk_src-3000-performance/ivb44 117124 ± 3% 117678 aim7/1BRD_48G-f2fs-disk_wrt-3000-performance/ivb44 3689 3616 aim7/1BRD_48G-f2fs-sync_disk_rw-600-performance/ivb44 70897 72758 aim7/1BRD_48G-xfs-creat-clo-1500-performance/ivb44 267649 ± 3% 270867 aim7/1BRD_48G-xfs-disk_cp-3000-performance/ivb44 485217 ± 3% 489403 aim7/1BRD_48G-xfs-disk_rd-9000-performance/ivb44 360451 359042 aim7/1BRD_48G-xfs-disk_rr-3000-performance/ivb44 338114 336838 aim7/1BRD_48G-xfs-disk_rw-3000-performance/ivb44 60130 ± 5% 4% 62663 aim7/1BRD_48G-xfs-disk_src-3000-performance/ivb44 403144 401476 aim7/1BRD_48G-xfs-disk_wrt-3000-performance/ivb44 26327 26513 aim7/1BRD_48G-xfs-sync_disk_rw-600-performance/ivb44 99091700659f4df9 1b5f2eb4a752e1fa7102f37545 ---------------- -------------------------- 2117 2138 GEO-MEAN fsmark.files_per_sec 4325 4379 fsmark/1x-1t-1BRD_32G-btrfs-4K-4G-fsyncBeforeClose-1fpd-performance/ivb43 9466 ± 3% 4% 9804 fsmark/1x-1t-1BRD_32G-ext4-4K-4G-fsyncBeforeClose-1fpd-performance/ivb43 433 ± 5% 424 fsmark/1x-1t-1BRD_48G-btrfs-4M-40G-NoSync-performance/ivb44 185 ± 6% 5% 194 fsmark/1x-1t-1BRD_48G-btrfs-4M-40G-fsyncBeforeClose-performance/ivb44 368 ± 3% -4% 355 ± 6% fsmark/1x-1t-1BRD_48G-ext4-4M-40G-NoSync-performance/ivb44 191 191 fsmark/1x-1t-1BRD_48G-ext4-4M-40G-fsyncBeforeClose-performance/ivb44 393 ± 4% 397 ± 4% fsmark/1x-1t-1BRD_48G-xfs-4M-40G-NoSync-performance/ivb44 200 201 fsmark/1x-1t-1BRD_48G-xfs-4M-40G-fsyncBeforeClose-performance/ivb44 924 -3% 896 ± 3% fsmark/1x-1t-1HDD-xfs-4K-400M-fsyncBeforeClose-1fpd-performance/ivb43 488 ± 3% 6% 516 fsmark/1x-64t-1BRD_48G-btrfs-4M-40G-NoSync-performance/ivb44 559 564 fsmark/1x-64t-1BRD_48G-ext4-4M-40G-NoSync-performance/ivb44 1130 1111 fsmark/1x-64t-1BRD_48G-ext4-4M-40G-fsyncBeforeClose-performance/ivb44 526 ± 7% 6% 557 fsmark/1x-64t-1BRD_48G-xfs-4M-40G-NoSync-performance/ivb44 1583 ± 3% 1620 fsmark/1x-64t-1BRD_48G-xfs-4M-40G-fsyncBeforeClose-performance/ivb44 33202 33208 fsmark/8-1SSD-16-ext4-8K-75G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 33889 33784 fsmark/8-1SSD-16-ext4-9B-48G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 25576 25509 fsmark/8-1SSD-32-xfs-9B-30G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 9117 9079 fsmark/8-1SSD-4-btrfs-8K-24G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 13288 13261 fsmark/8-1SSD-4-btrfs-9B-16G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 18851 ± 11% 11% 21013 fsmark/8-1SSD-4-f2fs-8K-72G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 24343 -4% 23473 ± 4% fsmark/8-1SSD-4-f2fs-9B-40G-fsyncBeforeClose-16d-256fpd-performance/lkp-hsw-ep4 Thanks, Fengguang