Hi, Filipe Manana > On Tue, Feb 2, 2021 at 5:42 AM Wang Yugui <wangyu...@e16-tech.com> wrote: > > > > Hi, Filipe Manana > > > > The dbench result with these patches is very good. thanks a lot. > > > > This is the dbench(synchronous mode) result , and then a question. > > > > command: dbench -s -t 60 -D /btrfs/ 32 > > mount option:ssd,space_cache=v2 > > kernel:5.10.12 + patchset 1 + this patchset > > patchset 1 and "this patchset" are the same, did you mean two > different patchsets or just a single patchset?
patchset1: btrfs: some performance improvements for dbench alike workloads patchset2: btrfs: more performance improvements for dbench workloads https://patchwork.kernel.org/project/linux-btrfs/list/?series=422801 I'm sorroy that I have replayed to the wrong patchset. > > > > > Question: > > for synchronous mode, the result type 1 is perfect? > > What do you mean by perfect? You mean if result 1 is better than result 2? In result 1, the MaxLat of Flush of dbench synchronous mode is fast as expected, the same level as kernel 5.4.91. But in result 2, the MaxLat of Flush of dbench synchronous mode is big as write level, but this is synchronous mode, most job should be done already before flush. > > and there is still some minor place about the flush to do for > > the result type2? > > By "minor place" you mean the huge difference I suppose. > > > > > > > result type 1: > > > > Operation Count AvgLat MaxLat > > ---------------------------------------- > > NTCreateX 868942 0.028 3.017 > > Close 638536 0.003 0.061 > > Rename 36851 0.663 4.000 > > Unlink 175182 0.399 5.358 > > Qpathinfo 789014 0.014 1.846 > > Qfileinfo 137684 0.002 0.047 > > Qfsinfo 144241 0.004 0.059 > > Sfileinfo 70913 0.008 0.046 > > Find 304554 0.057 1.889 > > ** WriteX 429696 3.960 2239.973 > > ReadX 1363356 0.005 0.358 > > LockX 2836 0.004 0.038 > > UnlockX 2836 0.002 0.018 > > ** Flush 60771 0.621 6.794 > > > > Throughput 452.385 MB/sec (sync open) 32 clients 32 procs > > max_latency=1963.312 ms > > + stat -f -c %T /btrfs/ > > btrfs > > + uname -r > > 5.10.12-4.el7.x86_64 > > > > > > result type 2: > > Operation Count AvgLat MaxLat > > ---------------------------------------- > > NTCreateX 888943 0.028 2.679 > > Close 652765 0.002 0.058 > > Rename 37705 0.572 3.962 > > Unlink 179713 0.383 3.983 > > Qpathinfo 806705 0.014 2.294 > > Qfileinfo 140752 0.002 0.125 > > Qfsinfo 147909 0.004 0.049 > > Sfileinfo 72374 0.008 0.104 > > Find 311839 0.058 2.305 > > ** WriteX 439656 3.854 1872.109 > > ReadX 1396868 0.005 0.324 > > LockX 2910 0.004 0.026 > > UnlockX 2910 0.002 0.025 > > ** Flush 62260 0.750 1659.364 > > > > Throughput 461.856 MB/sec (sync open) 32 clients 32 procs > > max_latency=1872.118 ms > > + stat -f -c %T /btrfs/ > > btrfs > > + uname -r > > 5.10.12-4.el7.x86_64 > > I'm not sure what your question is exactly. > > Are both results after applying the same patchset, or are they before > and after applying the patchset, respectively? Both result after applying the same patchset. and both on the same server, same SAS SSD disk. but the result is not stable, and the major diff is MaxLat of Flush. Server:Dell T7610 CPU: E5-2660 v2(10core 20threads) x2 SSD:TOSHIBA PX05SMQ040 Memory:192G (with ECC) > If they are both with the patchset applied, and you wonder about the > big variation in the "Flush" operations, I am not sure about why it is > so. > Both throughput and max latency are better in result 2. > > It's normal to have variations across dbench runs, I get them too, and > I do several runs (5 or 6) to check things out. > > I don't use virtualization (testing on bare metal), I set the cpu > governor mode to performance (instead of the "powersave" default) and > use a non-debug kernel configuration, because otherwise I get > significant variations in latencies and throughput too (though I never > got a huge difference such as from 6.794 to 1659.364). This is a bare metal(dell T7610). CPU mode is set to performance by BIOS. and I checked it by 'cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor' Maybe I used a SAS ssd, and the queue depth of SAS SSD is 254. smaller than 1023 of a NVMe SSD,but it is still enough for dbench 32 threads? The huge difference of MaxLat of Flush such as from 6.794 to 1659.364 is a problem. It is not easy to re-product both, mabye easy to reproduce the small one, maybe easy to reproduce the big one. Best Regards Wang Yugui (wangyu...@e16-tech.com) 2021/02/02
