Messages in this thread | | | Date | Tue, 15 Nov 2022 16:58:37 +0530 | Subject | Re: [PATCH v6 0/4] sched/fair: Improve scan efficiency of SIS | From | K Prateek Nayak <> |
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Hello Abel,
Thank you for taking a look at the report.
On 11/15/2022 2:01 PM, Abel Wu wrote: > Hi Prateek, thanks very much for your detailed testing! > > On 11/14/22 1:45 PM, K Prateek Nayak wrote: >> Hello Abel, >> >> Sorry for the delay. I've tested the patch on a dual socket Zen3 system >> (2 x 64C/128T) >> >> tl;dr >> >> o I do not notice any regressions with the standard benchmarks. >> o schbench sees a nice improvement to the tail latency when the number >> of worker are equal to the number of cores in the system in NPS1 and >> NPS2 mode. (Marked with "^") >> o Few data points show improvements in tbench in NPS1 and NPS2 mode. >> (Marked with "^") >> >> I'm still in the process of running larger workloads. If there is any >> specific workload you would like me to run on the test system, please >> do let me know. Below is the detailed report: > > Not particularly in my mind, and I think testing larger workloads is > great. Thanks! > >> >> Following are the results from running standard benchmarks on a >> dual socket Zen3 (2 x 64C/128T) machine configured in different >> NPS modes. >> >> NPS Modes are used to logically divide single socket into >> multiple NUMA region. >> Following is the NUMA configuration for each NPS mode on the system: >> >> NPS1: Each socket is a NUMA node. >> Total 2 NUMA nodes in the dual socket machine. >> >> Node 0: 0-63, 128-191 >> Node 1: 64-127, 192-255 >> >> NPS2: Each socket is further logically divided into 2 NUMA regions. >> Total 4 NUMA nodes exist over 2 socket. >> Node 0: 0-31, 128-159 >> Node 1: 32-63, 160-191 >> Node 2: 64-95, 192-223 >> Node 3: 96-127, 223-255 >> >> NPS4: Each socket is logically divided into 4 NUMA regions. >> Total 8 NUMA nodes exist over 2 socket. >> Node 0: 0-15, 128-143 >> Node 1: 16-31, 144-159 >> Node 2: 32-47, 160-175 >> Node 3: 48-63, 176-191 >> Node 4: 64-79, 192-207 >> Node 5: 80-95, 208-223 >> Node 6: 96-111, 223-231 >> Node 7: 112-127, 232-255 >> >> Benchmark Results: >> >> Kernel versions: >> - tip: 5.19.0 tip sched/core >> - sis_core: 5.19.0 tip sched/core + this series >> >> When we started testing, the tip was at: >> commit fdf756f71271 ("sched: Fix more TASK_state comparisons") >> >> ~~~~~~~~~~~~~ >> ~ hackbench ~ >> ~~~~~~~~~~~~~ >> >> o NPS1 >> >> Test: tip sis_core >> 1-groups: 4.06 (0.00 pct) 4.26 (-4.92 pct) * >> 1-groups: 4.14 (0.00 pct) 4.09 (1.20 pct) [Verification Run] >> 2-groups: 4.76 (0.00 pct) 4.71 (1.05 pct) >> 4-groups: 5.22 (0.00 pct) 5.11 (2.10 pct) >> 8-groups: 5.35 (0.00 pct) 5.31 (0.74 pct) >> 16-groups: 7.21 (0.00 pct) 6.80 (5.68 pct) >> >> o NPS2 >> >> Test: tip sis_core >> 1-groups: 4.09 (0.00 pct) 4.08 (0.24 pct) >> 2-groups: 4.70 (0.00 pct) 4.69 (0.21 pct) >> 4-groups: 5.05 (0.00 pct) 4.92 (2.57 pct) >> 8-groups: 5.35 (0.00 pct) 5.26 (1.68 pct) >> 16-groups: 6.37 (0.00 pct) 6.34 (0.47 pct) >> >> o NPS4 >> >> Test: tip sis_core >> 1-groups: 4.07 (0.00 pct) 3.99 (1.96 pct) >> 2-groups: 4.65 (0.00 pct) 4.59 (1.29 pct) >> 4-groups: 5.13 (0.00 pct) 5.00 (2.53 pct) >> 8-groups: 5.47 (0.00 pct) 5.43 (0.73 pct) >> 16-groups: 6.82 (0.00 pct) 6.56 (3.81 pct) > > Although each cpu will get 2.5 tasks when 16-groups, which can > be considered overloaded, I tested in AMD EPYC 7Y83 machine and > the total cpu usage was ~82% (with some older kernel version), > so there is still lots of idle time. > > I guess cutting off at 16-groups is because it's enough loaded > compared to the real workloads, so testing more groups might just > be a waste of time?
The machine has 16 LLCs so I capped the results at 16-groups. Previously I had seen some run-to-run variance with larger group counts so I limited the reports to 16-groups. I'll run hackbench with more number of groups (32, 64, 128, 256) and get back to you with the results along with results for a couple of long running workloads.
> > Thanks & Best Regards, > Abel > > [..snip..] >
-- Thanks and Regards, Prateek
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