Hi, I tried to run btrfs misc-next(5.11-rc6 +81patches) based on linux LTS 5.10.12 with the same other kernel components and the same kernel config.
Better dbench(sync open) result on both Throughput and max_latency. Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 958611 0.026 440.564 Close 703418 0.002 0.085 Rename 40599 0.518 439.825 Unlink 194095 0.282 439.792 Qpathinfo 869295 0.010 1.852 Qfileinfo 151285 0.002 0.095 Qfsinfo 159492 0.004 0.051 Sfileinfo 78078 0.010 0.104 Find 335905 0.036 3.043 WriteX 473353 3.637 713.039 ReadX 1502197 0.005 0.752 LockX 3100 0.004 0.024 UnlockX 3100 0.002 0.020 Flush 67264 0.575 363.550 Throughput 497.551 MB/sec (sync open) 32 clients 32 procs max_latency=713.045 ms detail: 32 34620 506.62 MB/sec execute 1 sec latency 6.860 ms 32 37878 528.91 MB/sec execute 2 sec latency 6.366 ms 32 41015 541.17 MB/sec execute 3 sec latency 6.326 ms 32 43981 539.10 MB/sec execute 4 sec latency 6.743 ms 32 47111 540.92 MB/sec execute 5 sec latency 7.597 ms 32 50163 544.44 MB/sec execute 6 sec latency 6.984 ms 32 52952 532.23 MB/sec execute 7 sec latency 63.769 ms 32 55561 514.29 MB/sec execute 8 sec latency 482.822 ms 32 58415 515.72 MB/sec execute 9 sec latency 6.238 ms 32 61365 515.94 MB/sec execute 10 sec latency 8.102 ms 32 64309 518.10 MB/sec execute 11 sec latency 6.176 ms 32 67322 517.59 MB/sec execute 12 sec latency 6.690 ms 32 70343 515.28 MB/sec execute 13 sec latency 6.831 ms 32 73323 512.81 MB/sec execute 14 sec latency 7.754 ms 32 76151 513.38 MB/sec execute 15 sec latency 7.275 ms 32 79042 513.44 MB/sec execute 16 sec latency 6.678 ms 32 81995 514.71 MB/sec execute 17 sec latency 8.393 ms 32 84911 512.80 MB/sec execute 18 sec latency 7.574 ms 32 87884 510.68 MB/sec execute 19 sec latency 8.363 ms 32 89711 502.50 MB/sec execute 20 sec latency 695.270 ms *1 32 92628 503.68 MB/sec execute 21 sec latency 7.405 ms 32 95627 503.66 MB/sec execute 22 sec latency 6.545 ms 32 98638 502.90 MB/sec execute 23 sec latency 6.649 ms 32 101641 503.29 MB/sec execute 24 sec latency 7.740 ms 32 104515 503.72 MB/sec execute 25 sec latency 6.941 ms 32 107448 504.28 MB/sec execute 26 sec latency 6.704 ms 32 110321 504.79 MB/sec execute 27 sec latency 6.216 ms 32 113235 503.77 MB/sec execute 28 sec latency 7.366 ms 32 116185 503.18 MB/sec execute 29 sec latency 7.153 ms 32 119074 503.35 MB/sec execute 30 sec latency 7.026 ms 32 121970 503.51 MB/sec execute 31 sec latency 8.789 ms 32 123948 498.76 MB/sec execute 32 sec latency 539.597 ms *2 32 127045 499.14 MB/sec execute 33 sec latency 6.112 ms 32 130059 499.66 MB/sec execute 34 sec latency 7.762 ms 32 133062 500.45 MB/sec execute 35 sec latency 6.706 ms 32 136014 501.03 MB/sec execute 36 sec latency 8.384 ms 32 139018 502.13 MB/sec execute 37 sec latency 6.822 ms 32 142047 502.50 MB/sec execute 38 sec latency 6.924 ms 32 144935 501.74 MB/sec execute 39 sec latency 7.319 ms 32 147836 501.38 MB/sec execute 40 sec latency 6.958 ms 32 150677 501.36 MB/sec execute 41 sec latency 6.993 ms 32 153562 501.63 MB/sec execute 42 sec latency 7.126 ms 32 156385 501.63 MB/sec execute 43 sec latency 7.602 ms 32 159258 500.99 MB/sec execute 44 sec latency 7.281 ms 32 162248 501.05 MB/sec execute 45 sec latency 6.896 ms 32 165128 501.12 MB/sec execute 46 sec latency 7.134 ms 32 168070 501.39 MB/sec execute 47 sec latency 6.674 ms 32 169978 497.76 MB/sec execute 48 sec latency 355.037 ms 32 172936 497.92 MB/sec execute 49 sec latency 713.045 ms *3 32 175828 497.93 MB/sec execute 50 sec latency 6.585 ms 32 178731 498.06 MB/sec execute 51 sec latency 8.511 ms 32 181681 498.79 MB/sec execute 52 sec latency 7.093 ms 32 184622 498.83 MB/sec execute 53 sec latency 6.265 ms 32 187647 498.90 MB/sec execute 54 sec latency 6.902 ms 32 190125 497.59 MB/sec execute 55 sec latency 142.628 ms 32 192920 497.36 MB/sec execute 56 sec latency 432.224 ms 32 195822 497.85 MB/sec execute 57 sec latency 6.497 ms 32 198709 497.56 MB/sec execute 58 sec latency 6.418 ms 32 201665 497.55 MB/sec execute 59 sec latency 6.699 ms Because of kernel interface changed between 5.10 and 5.11 , so we need some modify to btrfs misc-next(5.11-rc6 +81patches) to run on linux LTS 5.10.12, # drop 0001-block-add-a-bdev_kobj-helper.patch # drop 0001-block-remove-i_bdev.patch # add 0001-btrfs-bdev_nr_sectors.patch Best Regards Wang Yugui (wangyu...@e16-tech.com) 2021/02/04 > Hi, > > There is the dbench(sync open) test result of misc-next(5.11-rc6 +81patches) > > 1, the MaxLat is changed from 1900ms level to 1000ms level. > that is a good improvement. > > 2, It is OK that NTCreateX/Rename/Unlink/WriteX have the same level of > MaxLat because all of them will write something to disk. > > 3, I'm not sure whether MaxLat of Flush is OK. > there should be nothing to write for Flush because of > dbench(sync open) mode. but I'm not sure whether some > scsi comand such as Synchronize Cache will be executed by Flush. > > Operation Count AvgLat MaxLat > ---------------------------------------- > NTCreateX 924298 0.035 745.523 > Close 678499 0.002 0.093 > Rename 39280 0.597 744.714 > Unlink 187119 0.435 745.547 > Qpathinfo 838558 0.013 0.978 > Qfileinfo 146308 0.002 0.055 > Qfsinfo 154172 0.004 0.108 > Sfileinfo 75423 0.010 0.109 > Find 324478 0.050 1.115 > WriteX 457376 3.665 957.922 > ReadX 1454051 0.005 0.131 > LockX 3032 0.004 0.027 > UnlockX 3032 0.002 0.022 > Flush 64867 0.649 718.676 > > Throughput 481.002 MB/sec (sync open) 32 clients 32 procs > max_latency=957.929 ms > + stat -f -c %T /btrfs/ > btrfs > + uname -r > 5.11.0-0.rc6.141.el8.x86_64 > > detail: > 32 33682 548.70 MB/sec execute 1 sec latency 7.024 ms > 32 36692 538.41 MB/sec execute 2 sec latency 6.719 ms > 32 39787 544.75 MB/sec execute 3 sec latency 6.405 ms > 32 42850 540.09 MB/sec execute 4 sec latency 7.717 ms > 32 45872 535.64 MB/sec execute 5 sec latency 7.271 ms > 32 48861 524.29 MB/sec execute 6 sec latency 6.685 ms > 32 51343 512.54 MB/sec execute 7 sec latency 128.666 ms > 32 53366 496.73 MB/sec execute 8 sec latency 703.255 ms *1 > 32 56428 498.60 MB/sec execute 9 sec latency 6.346 ms > 32 59471 498.40 MB/sec execute 10 sec latency 9.958 ms > 32 62175 495.68 MB/sec execute 11 sec latency 14.270 ms > 32 65143 498.90 MB/sec execute 12 sec latency 9.391 ms > 32 68116 502.19 MB/sec execute 13 sec latency 5.713 ms > 32 71078 501.45 MB/sec execute 14 sec latency 6.235 ms > 32 74030 500.43 MB/sec execute 15 sec latency 7.135 ms > 32 76908 500.82 MB/sec execute 16 sec latency 7.071 ms > 32 79794 499.61 MB/sec execute 17 sec latency 7.556 ms > 32 82791 502.30 MB/sec execute 18 sec latency 6.509 ms > 32 85676 502.05 MB/sec execute 19 sec latency 6.938 ms > 32 86950 486.44 MB/sec execute 20 sec latency 554.015 ms *2 > 32 89670 487.60 MB/sec execute 21 sec latency 901.490 ms *3 > 32 92577 487.64 MB/sec execute 22 sec latency 6.715 ms > 32 95528 488.03 MB/sec execute 23 sec latency 7.457 ms > 32 98507 488.76 MB/sec execute 24 sec latency 7.266 ms > 32 101340 488.76 MB/sec execute 25 sec latency 6.699 ms > 32 104331 489.94 MB/sec execute 26 sec latency 6.506 ms > 32 107166 490.87 MB/sec execute 27 sec latency 6.582 ms > 32 110022 490.17 MB/sec execute 28 sec latency 7.072 ms > 32 112931 490.34 MB/sec execute 29 sec latency 6.484 ms > 32 115658 489.67 MB/sec execute 30 sec latency 6.767 ms > 32 118569 490.14 MB/sec execute 31 sec latency 6.825 ms > 32 121334 490.34 MB/sec execute 32 sec latency 7.270 ms > 32 124182 489.95 MB/sec execute 33 sec latency 6.849 ms > 32 127073 490.05 MB/sec execute 34 sec latency 6.934 ms > 32 129835 489.56 MB/sec execute 35 sec latency 7.455 ms > 32 130952 481.58 MB/sec execute 36 sec latency 635.676 ms *4 > 32 133736 481.74 MB/sec execute 37 sec latency 957.929 ms *5 > 32 136646 481.79 MB/sec execute 38 sec latency 7.339 ms > 32 139616 483.23 MB/sec execute 39 sec latency 7.199 ms > 32 142526 483.62 MB/sec execute 40 sec latency 7.344 ms > 32 145429 483.58 MB/sec execute 41 sec latency 6.967 ms > 32 148329 484.09 MB/sec execute 42 sec latency 8.043 ms > 32 151091 483.89 MB/sec execute 43 sec latency 7.476 ms > 32 153913 484.33 MB/sec execute 44 sec latency 7.611 ms > 32 156679 484.29 MB/sec execute 45 sec latency 7.612 ms > 32 159534 483.90 MB/sec execute 46 sec latency 8.295 ms > 32 162328 484.17 MB/sec execute 47 sec latency 6.582 ms > 32 165080 483.64 MB/sec execute 48 sec latency 8.939 ms > 32 167861 484.12 MB/sec execute 49 sec latency 6.684 ms > 32 170616 483.56 MB/sec execute 50 sec latency 7.051 ms > 32 173557 483.89 MB/sec execute 51 sec latency 6.923 ms > 32 176424 484.52 MB/sec execute 52 sec latency 6.689 ms > 32 179255 484.14 MB/sec execute 53 sec latency 7.973 ms > 32 181195 481.47 MB/sec execute 54 sec latency 305.495 ms > 32 183309 479.62 MB/sec execute 55 sec latency 866.862 ms *6 > 32 186256 479.82 MB/sec execute 56 sec latency 7.016 ms > 32 189209 480.82 MB/sec execute 57 sec latency 6.789 ms > 32 192072 480.93 MB/sec execute 58 sec latency 7.305 ms > 32 195054 481.00 MB/sec execute 59 sec latency 7.432 ms > > > Best Regards > Wang Yugui (wangyu...@e16-tech.com) > 2021/02/03 > > > > > > > On 3.02.21 г. 12:51 ч., Filipe Manana wrote: > > > On Tue, Feb 2, 2021 at 2:15 PM Wang Yugui <wangyu...@e16-tech.com> wrote: > > >> > > >> Hi, Filipe Manana > > >> > > >> There are some dbench(sync mode) result on the same hardware, > > >> but with different linux kernel > > >> > > >> 4.14.200 > > >> Operation Count AvgLat MaxLat > > >> ---------------------------------------- > > >> WriteX 225281 5.163 82.143 > > >> Flush 32161 2.250 62.669 > > >> Throughput 236.719 MB/sec (sync open) 32 clients 32 procs > > >> max_latency=82.149 ms > > >> > > >> 4.19.21 > > >> Operation Count AvgLat MaxLat > > >> ---------------------------------------- > > >> WriteX 118842 10.946 116.345 > > >> Flush 16506 0.115 44.575 > > >> Throughput 125.973 MB/sec (sync open) 32 clients 32 procs > > >> max_latency=116.390 ms > > >> > > >> 4.19.150 > > >> Operation Count AvgLat MaxLat > > >> ---------------------------------------- > > >> WriteX 144509 9.151 117.353 > > >> lush 20563 0.128 52.014 > > >> Throughput 153.707 MB/sec (sync open) 32 clients 32 procs > > >> max_latency=117.379 ms > > >> > > >> 5.4.91 > > >> Operation Count AvgLat MaxLat > > >> ---------------------------------------- > > >> WriteX 367033 4.377 1908.724 > > >> Flush 52037 0.159 39.871 > > >> Throughput 384.554 MB/sec (sync open) 32 clients 32 procs > > >> max_latency=1908.968 ms > > > > > > Ok, it seems somewhere between 4.19 and 5.4, something made the > > > latency much worse for you at least. > > > > > > Is it only when using sync open (O_SYNC, dbench's -s flag), what about > > > when not using it? > > > > > > I'll have to look at it, but it will likely take some time. > > > > > > This seems like the perf regression I observed starting with kernel 5.0, > > essentially preemptive flush of metadata was broken for quite some time, > > but kernel 5.0 removed a btrfs_end_transaction call from > > should_end_transaction which unmasked the issue. > > > > In particular this should have been fixed by the following commit in > > misc-next: > > > > https://github.com/kdave/btrfs-devel/commit/28d7e221e4323a5b98e5d248eb5603ff5206a188 > > which is part of a larger series of patches. So Wang, in order to test > > this hypothesis can you re-run those tests with the latest misc-next > > branch . > > > > <snip> >
