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Date: Mon, 28 Nov 2022 17:21:32 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Vincent Guittot <vincent.guittot@...aro.org>, mingo@...hat.com,
peterz@...radead.org, juri.lelli@...hat.com,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
linux-kernel@...r.kernel.org, parth@...ux.ibm.com
Cc: qyousef@...alina.io, chris.hyser@...cle.com,
patrick.bellasi@...bug.net, David.Laight@...lab.com,
pjt@...gle.com, pavel@....cz, tj@...nel.org, qperret@...gle.com,
tim.c.chen@...ux.intel.com, joshdon@...gle.com, timj@....org,
yu.c.chen@...el.com, youssefesmat@...omium.org,
joel@...lfernandes.org
Subject: Re: [PATCH v9 0/9] Add latency priority for CFS class
Hello Vincent,
Following are the test results on dual socket Zen3 machine (2 x 64C/128T)
tl;dr
o All benchmarks with DEFAULT_LATENCY_NICE value are comparable to tip.
There is, however, a noticeable dip for unixbench-spawn test case.
o With the 2 rbtree approach, I do not see much difference in the
hackbench results with varying latency nice value. Tests on v5 did
yield noticeable improvements for hackbench.
(https://lore.kernel.org/lkml/cd48ebbb-9724-985f-28e3-e558dea07827@amd.com/)
o For hackbench + cyclictest and hackbench + schbench, I see the
expected behavior with different latency nice values.
o There are a few cases with hackbench and hackbench + cyclictest where
the results are non-monotonic with different latency nice values.
(Marked with "^").
I'll leave the detailed results below:
On 11/15/2022 10:48 PM, Vincent Guittot wrote:
> This patchset restarts the work about adding a latency priority to describe
> the latency tolerance of cfs tasks.
>
> Patch [1] is a new one that has been added with v6. It fixes an
> unfairness for low prio tasks because of wakeup_gran() being bigger
> than the maximum vruntime credit that a waking task can keep after
> sleeping.
>
> The patches [2-4] have been done by Parth:
> https://lore.kernel.org/lkml/20200228090755.22829-1-parth@linux.ibm.com/
>
> I have just rebased and moved the set of latency priority outside the
> priority update. I have removed the reviewed tag because the patches
> are 2 years old.
>
> This aims to be a generic interface and the following patches is one use
> of it to improve the scheduling latency of cfs tasks.
>
> Patch [5] uses latency nice priority to define a latency offset
> and then decide if a cfs task can or should preempt the current
> running task. The patch gives some tests results with cyclictests and
> hackbench to highlight the benefit of latency priority for short
> interactive task or long intensive tasks.
>
> Patch [6] adds the support of latency nice priority to task group by
> adding a cpu.latency.nice field. The range is [-20:19] as for setting task
> latency priority.
>
> Patch [7] makes sched_core taking into account the latency offset.
>
> Patch [8] adds a rb tree to cover some corner cases where the latency
> sensitive task (priority < 0) is preempted by high priority task (RT/DL)
> or fails to preempt them. This patch ensures that tasks will have at least
> a slice of sched_min_granularity in priority at wakeup.
>
> Patch [9] removes useless check after adding a latency rb tree.
>
> I have also backported the patchset on a dragonboard RB3 with an android
> mainline kernel based on v5.18 for a quick test. I have used the
> TouchLatency app which is part of AOSP and described to be a very good
> test to highlight jitter and jank frame sources of a system [1].
> In addition to the app, I have added some short running tasks waking-up
> regularly (to use the 8 cpus for 4 ms every 37777us) to stress the system
> without overloading it (and disabling EAS). The 1st results shows that the
> patchset helps to reduce the missed deadline frames from 5% to less than
> 0.1% when the cpu.latency.nice of task group are set. I haven't rerun the
> test with latest version.
>
> I have also tested the patchset with the modified version of the alsa
> latency test that has been shared by Tim. The test quickly xruns with
> default latency nice priority 0 but is able to run without underuns with
> a latency -20 and hackbench running simultaneously.
>
> While preparing the version 8, I have evaluated the benefit of using an
> augmented rbtree instead of adding a rbtree for latency sensitive entities,
> which was a relevant suggestion done by PeterZ. Although the augmented
> rbtree enables to sort additional information in the tree with a limited
> overhead, it has more impact on legacy use cases (latency_nice >= 0)
> because the augmented callbacks are always called to maintain this
> additional information even when there is no sensitive tasks. In such
> cases, the dedicated rbtree remains empty and the overhead is reduced to
> loading a cached null node pointer. Nevertheless, we might want to
> reconsider the augmented rbtree once the use of negative latency_nice will
> be more widlely deployed. At now, the different tests that I have done,
> have not shown improvements with augmented rbtree.
>
> Below are some hackbench results:
> 2 rbtrees augmented rbtree augmented rbtree
> sorted by vruntime sorted by wakeup_vruntime
> sched pipe
> avg 26311,000 25976,667 25839,556
> stdev 0,15 % 0,28 % 0,24 %
> vs tip 0,50 % -0,78 % -1,31 %
> hackbench 1 group
> avg 1,315 1,344 1,359
> stdev 0,88 % 1,55 % 1,82 %
> vs tip -0,47 % -2,68 % -3,87 %
> hackbench 4 groups
> avg 1,339 1,365 1,367
> stdev 2,39 % 2,26 % 3,58 %
> vs tip -0,08 % -2,01 % -2,22 %
> hackbench 8 groups
> avg 1,233 1,286 1,301
> stdev 0,74 % 1,09 % 1,52 %
> vs tip 0,29 % -4,05 % -5,27 %
> hackbench 16 groups
> avg 1,268 1,313 1,319
> stdev 0,85 % 1,60 % 0,68 %
> vs tip -0,02 % -3,56 % -4,01 %
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: 6.1.0 tip sched/core
- latency_nice: 6.1.0 tip sched/core + this series
When we started testing, the tip was at:
commit d6962c4fe8f9 "sched: Clear ttwu_pending after enqueue_task()"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ hackbench - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NPS1
Test: tip latency_nice
1-groups: 4.25 (0.00 pct) 4.14 (2.58 pct)
2-groups: 4.95 (0.00 pct) 4.92 (0.60 pct)
4-groups: 5.19 (0.00 pct) 5.18 (0.19 pct)
8-groups: 5.45 (0.00 pct) 5.44 (0.18 pct)
16-groups: 7.33 (0.00 pct) 7.32 (0.13 pct)
NPS2
Test: tip latency_nice
1-groups: 4.09 (0.00 pct) 4.08 (0.24 pct)
2-groups: 4.68 (0.00 pct) 4.72 (-0.85 pct)
4-groups: 5.05 (0.00 pct) 4.97 (1.58 pct)
8-groups: 5.37 (0.00 pct) 5.34 (0.55 pct)
16-groups: 6.69 (0.00 pct) 6.74 (-0.74 pct)
NPS4
Test: tip latency_nice
1-groups: 4.28 (0.00 pct) 4.35 (-1.63 pct)
2-groups: 4.78 (0.00 pct) 4.76 (0.41 pct)
4-groups: 5.11 (0.00 pct) 5.06 (0.97 pct)
8-groups: 5.48 (0.00 pct) 5.40 (1.45 pct)
16-groups: 7.07 (0.00 pct) 6.70 (5.23 pct)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ schbench - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NPS1
#workers: tip latency_nice
1: 31.00 (0.00 pct) 32.00 (-3.22 pct)
2: 33.00 (0.00 pct) 34.00 (-3.03 pct)
4: 39.00 (0.00 pct) 38.00 (2.56 pct)
8: 45.00 (0.00 pct) 46.00 (-2.22 pct)
16: 61.00 (0.00 pct) 66.00 (-8.19 pct)
32: 108.00 (0.00 pct) 110.00 (-1.85 pct)
64: 212.00 (0.00 pct) 216.00 (-1.88 pct)
128: 475.00 (0.00 pct) 701.00 (-47.57 pct) *
128: 429.00 (0.00 pct) 441.00 (-2.79 pct) [Verification Run]
256: 44736.00 (0.00 pct) 45632.00 (-2.00 pct)
512: 77184.00 (0.00 pct) 78720.00 (-1.99 pct)
NPS2
#workers: tip latency_nice
1: 28.00 (0.00 pct) 33.00 (-17.85 pct)
2: 34.00 (0.00 pct) 31.00 (8.82 pct)
4: 36.00 (0.00 pct) 36.00 (0.00 pct)
8: 51.00 (0.00 pct) 49.00 (3.92 pct)
16: 68.00 (0.00 pct) 64.00 (5.88 pct)
32: 113.00 (0.00 pct) 115.00 (-1.76 pct)
64: 221.00 (0.00 pct) 219.00 (0.90 pct)
128: 553.00 (0.00 pct) 531.00 (3.97 pct)
256: 43840.00 (0.00 pct) 48192.00 (-9.92 pct) *
256: 50427.00 (0.00 pct) 48351.00 (4.11 pct) [Verification Run]
512: 76672.00 (0.00 pct) 81024.00 (-5.67 pct)
NPS4
#workers: tip latency_nice
1: 33.00 (0.00 pct) 28.00 (15.15 pct)
2: 29.00 (0.00 pct) 34.00 (-17.24 pct)
4: 39.00 (0.00 pct) 36.00 (7.69 pct)
8: 58.00 (0.00 pct) 55.00 (5.17 pct)
16: 66.00 (0.00 pct) 67.00 (-1.51 pct)
32: 112.00 (0.00 pct) 116.00 (-3.57 pct)
64: 215.00 (0.00 pct) 213.00 (0.93 pct)
128: 689.00 (0.00 pct) 571.00 (17.12 pct)
256: 45120.00 (0.00 pct) 46400.00 (-2.83 pct)
512: 77440.00 (0.00 pct) 76160.00 (1.65 pct)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ tbench - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NPS1
Clients: tip latency_nice
1 581.75 (0.00 pct) 586.52 (0.81 pct)
2 1145.75 (0.00 pct) 1160.69 (1.30 pct)
4 2127.94 (0.00 pct) 2141.49 (0.63 pct)
8 3838.27 (0.00 pct) 3721.10 (-3.05 pct)
16 6272.71 (0.00 pct) 6539.82 (4.25 pct)
32 11400.12 (0.00 pct) 12079.49 (5.95 pct)
64 21605.96 (0.00 pct) 22908.83 (6.03 pct)
128 30715.43 (0.00 pct) 31736.95 (3.32 pct)
256 55580.78 (0.00 pct) 54786.29 (-1.42 pct)
512 56528.79 (0.00 pct) 56453.54 (-0.13 pct)
1024 56520.40 (0.00 pct) 56369.93 (-0.26 pct)
NPS2
Clients: tip latency_nice
1 584.13 (0.00 pct) 582.53 (-0.27 pct)
2 1153.63 (0.00 pct) 1140.27 (-1.15 pct)
4 2212.89 (0.00 pct) 2159.49 (-2.41 pct)
8 3871.35 (0.00 pct) 3840.77 (-0.78 pct)
16 6216.72 (0.00 pct) 6437.98 (3.55 pct)
32 11766.98 (0.00 pct) 11663.53 (-0.87 pct)
64 22000.93 (0.00 pct) 21882.88 (-0.53 pct)
128 31520.53 (0.00 pct) 31147.05 (-1.18 pct)
256 51420.11 (0.00 pct) 55216.39 (7.38 pct)
512 53935.90 (0.00 pct) 55407.60 (2.72 pct)
1024 55239.73 (0.00 pct) 55997.25 (1.37 pct)
NPS4
Clients: tip latency_nice
1 585.83 (0.00 pct) 578.17 (-1.30 pct)
2 1141.59 (0.00 pct) 1131.14 (-0.91 pct)
4 2174.79 (0.00 pct) 2086.52 (-4.05 pct)
8 3887.56 (0.00 pct) 3778.47 (-2.80 pct)
16 6441.59 (0.00 pct) 6364.30 (-1.19 pct)
32 12133.60 (0.00 pct) 11465.26 (-5.50 pct) *
32 11677.16 (0.00 pct) 12662.09 (8.43 pct) [Verification Run]
64 21769.15 (0.00 pct) 19488.45 (-10.47 pct) *
64 20305.64 (0.00 pct) 21002.90 (3.43 pct) [Verification Run]
128 31396.31 (0.00 pct) 31177.37 (-0.69 pct)
256 52792.39 (0.00 pct) 52890.41 (0.18 pct)
512 55315.44 (0.00 pct) 53572.65 (-3.15 pct)
1024 52150.27 (0.00 pct) 54079.48 (3.69 pct)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ stream - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NPS1
10 Runs:
Test: tip latency_nice
Copy: 307827.79 (0.00 pct) 330524.48 (7.37 pct)
Scale: 208872.28 (0.00 pct) 215002.06 (2.93 pct)
Add: 239404.64 (0.00 pct) 230334.74 (-3.78 pct)
Triad: 247258.30 (0.00 pct) 238505.06 (-3.54 pct)
100 Runs:
Test: tip latency_nice
Copy: 317217.55 (0.00 pct) 314467.62 (-0.86 pct)
Scale: 208740.82 (0.00 pct) 210452.00 (0.81 pct)
Add: 240550.63 (0.00 pct) 232376.03 (-3.39 pct)
Triad: 249594.21 (0.00 pct) 242460.83 (-2.85 pct)
NPS2
10 Runs:
Test: tip latency_nice
Copy: 340877.18 (0.00 pct) 339441.26 (-0.42 pct)
Scale: 217318.16 (0.00 pct) 216905.49 (-0.18 pct)
Add: 259078.93 (0.00 pct) 261686.67 (1.00 pct)
Triad: 274500.78 (0.00 pct) 271699.83 (-1.02 pct)
100 Runs:
Test: tip latency_nice
Copy: 341860.73 (0.00 pct) 335826.36 (-1.76 pct)
Scale: 218043.00 (0.00 pct) 216451.84 (-0.72 pct)
Add: 253698.22 (0.00 pct) 257317.72 (1.42 pct)
Triad: 265011.84 (0.00 pct) 267769.93 (1.04 pct)
NPS4
10 Runs:
Test: tip latency_nice
Copy: 340877.18 (0.00 pct) 365921.51 (7.34 pct)
Scale: 217318.16 (0.00 pct) 239408.65 (10.16 pct)
Add: 259078.93 (0.00 pct) 264859.31 (2.23 pct)
Triad: 274500.78 (0.00 pct) 281543.65 (2.56 pct)
100 Runs:
Test: tip latency_nice
Copy: 341860.73 (0.00 pct) 359255.16 (5.08 pct)
Scale: 218043.00 (0.00 pct) 238154.15 (9.22 pct)
Add: 253698.22 (0.00 pct) 269223.49 (6.11 pct)
Triad: 265011.84 (0.00 pct) 278473.85 (5.07 pct)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ ycsb-mongodb - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
o NPS1
tip: 131244.00 (var: 2.67%)
latency_nice: 132118.00 (var: 3.62%) (+0.66%)
o NPS2
tip: 127663.33 (var: 2.08%)
latency_nice: 129148.00 (var: 4.29%) (+1.16%)
o NPS4
tip: 133295.00 (var: 1.58%)
latency_nice: 129975.33 (var: 1.10%) (-2.49%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ Unixbench - DEFAULT_LATENCY_NICE ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
o NPS1
Test Metric Parallelism tip latency_nice
unixbench-dhry2reg Hmean unixbench-dhry2reg-1 48929419.48 ( 0.00%) 49137039.06 ( 0.42%)
unixbench-dhry2reg Hmean unixbench-dhry2reg-512 6275526953.25 ( 0.00%) 6265580479.15 ( -0.16%)
unixbench-syscall Amean unixbench-syscall-1 2994319.73 ( 0.00%) 3008596.83 * -0.48%*
unixbench-syscall Amean unixbench-syscall-512 7349715.87 ( 0.00%) 7420994.50 * -0.97%*
unixbench-pipe Hmean unixbench-pipe-1 2830206.03 ( 0.00%) 2854405.99 * 0.86%*
unixbench-pipe Hmean unixbench-pipe-512 326207828.01 ( 0.00%) 328997804.52 * 0.86%*
unixbench-spawn Hmean unixbench-spawn-1 6394.21 ( 0.00%) 6367.75 ( -0.41%)
unixbench-spawn Hmean unixbench-spawn-512 72700.64 ( 0.00%) 71454.19 * -1.71%*
unixbench-execl Hmean unixbench-execl-1 4723.61 ( 0.00%) 4750.59 ( 0.57%)
unixbench-execl Hmean unixbench-execl-512 11212.05 ( 0.00%) 11262.13 ( 0.45%)
o NPS2
Test Metric Parallelism tip latency_nice
unixbench-dhry2reg Hmean unixbench-dhry2reg-1 49271512.85 ( 0.00%) 49245260.43 ( -0.05%)
unixbench-dhry2reg Hmean unixbench-dhry2reg-512 6267992483.03 ( 0.00%) 6264951100.67 ( -0.05%)
unixbench-syscall Amean unixbench-syscall-1 2995885.93 ( 0.00%) 3005975.10 * -0.34%*
unixbench-syscall Amean unixbench-syscall-512 7388865.77 ( 0.00%) 7276275.63 * 1.52%*
unixbench-pipe Hmean unixbench-pipe-1 2828971.95 ( 0.00%) 2856578.72 * 0.98%*
unixbench-pipe Hmean unixbench-pipe-512 326225385.37 ( 0.00%) 328941270.81 * 0.83%*
unixbench-spawn Hmean unixbench-spawn-1 6958.71 ( 0.00%) 6954.21 ( -0.06%)
unixbench-spawn Hmean unixbench-spawn-512 85443.56 ( 0.00%) 70536.42 * -17.45%* (0.67% vs 0.93% - CoEff var)
unixbench-execl Hmean unixbench-execl-1 4767.99 ( 0.00%) 4752.63 * -0.32%*
unixbench-execl Hmean unixbench-execl-512 11250.72 ( 0.00%) 11320.97 ( 0.62%)
o NPS4
Test Metric Parallelism tip latency_nice
unixbench-dhry2reg Hmean unixbench-dhry2reg-1 49041932.68 ( 0.00%) 49156671.05 ( 0.23%)
unixbench-dhry2reg Hmean unixbench-dhry2reg-512 6286981589.85 ( 0.00%) 6285248711.40 ( -0.03%)
unixbench-syscall Amean unixbench-syscall-1 2992405.60 ( 0.00%) 3008933.03 * -0.55%*
unixbench-syscall Amean unixbench-syscall-512 7971789.70 ( 0.00%) 7814622.23 * 1.97%*
unixbench-pipe Hmean unixbench-pipe-1 2822892.54 ( 0.00%) 2852615.11 * 1.05%*
unixbench-pipe Hmean unixbench-pipe-512 326408309.83 ( 0.00%) 329617202.56 * 0.98%*
unixbench-spawn Hmean unixbench-spawn-1 7685.31 ( 0.00%) 7243.54 ( -5.75%)
unixbench-spawn Hmean unixbench-spawn-512 72245.56 ( 0.00%) 77000.81 * 6.58%*
unixbench-execl Hmean unixbench-execl-1 4761.42 ( 0.00%) 4733.12 * -0.59%*
unixbench-execl Hmean unixbench-execl-512 11533.53 ( 0.00%) 11660.17 ( 1.10%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ Hackbench - Various Latency Nice Values ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
o 100000 loops
- pipe (process)
Test: LN: 0 LN: 19 LN: -20
1-groups: 3.91 (0.00 pct) 3.91 (0.00 pct) 3.81 (2.55 pct)
2-groups: 4.48 (0.00 pct) 4.52 (-0.89 pct) 4.53 (-1.11 pct)
4-groups: 4.83 (0.00 pct) 4.83 (0.00 pct) 4.87 (-0.82 pct)
8-groups: 5.09 (0.00 pct) 5.00 (1.76 pct) 5.07 (0.39 pct)
16-groups: 6.92 (0.00 pct) 6.79 (1.87 pct) 6.96 (-0.57 pct)
- pipe (thread)
1-groups: 4.13 (0.00 pct) 4.08 (1.21 pct) 4.11 (0.48 pct)
2-groups: 4.78 (0.00 pct) 4.90 (-2.51 pct) 4.79 (-0.20 pct)
4-groups: 5.12 (0.00 pct) 5.08 (0.78 pct) 5.16 (-0.78 pct)
8-groups: 5.31 (0.00 pct) 5.28 (0.56 pct) 5.33 (-0.37 pct)
16-groups: 7.34 (0.00 pct) 7.27 (0.95 pct) 7.33 (0.13 pct)
- socket (process)
Test: LN: 0 LN: 19 LN: -20
1-groups: 6.61 (0.00 pct) 6.38 (3.47 pct) 6.54 (1.05 pct)
2-groups: 6.59 (0.00 pct) 6.67 (-1.21 pct) 6.11 (7.28 pct)
4-groups: 6.77 (0.00 pct) 6.78 (-0.14 pct) 6.79 (-0.29 pct)
8-groups: 8.29 (0.00 pct) 8.39 (-1.20 pct) 8.36 (-0.84 pct)
16-groups: 12.21 (0.00 pct) 12.03 (1.47 pct) 12.35 (-1.14 pct)
- socket (thread)
Test: LN: 0 LN: 19 LN: -20
1-groups: 6.50 (0.00 pct) 5.99 (7.84 pct) 6.02 (7.38 pct) ^
2-groups: 6.07 (0.00 pct) 6.20 (-2.14 pct) 6.23 (-2.63 pct)
4-groups: 6.61 (0.00 pct) 6.64 (-0.45 pct) 6.63 (-0.30 pct)
8-groups: 8.87 (0.00 pct) 8.67 (2.25 pct) 8.78 (1.01 pct)
16-groups: 12.63 (0.00 pct) 12.54 (0.71 pct) 12.59 (0.31 pct)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ Hackbench + Cyclictest - Various Latency Nice Values ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Hackbench: 32 Groups
perf bench sched messaging -p -l 100000 -g 32&
cyclictest --policy other -D 5 -q -n -h 2000
o NPS1
----------------------------------------------------------------------------------------------------------
| Hackbench | Cyclictest LN = 19 | Cyclictest LN = 0 | Cyclictest LN = -20 |
| LN |------------------------------|-------------------------------|---------------------------|
| | Min | Avg | Max | Min | Avg | Max | Min | Avg | Max |
|-------------|--------|---------|-----------|--------|---------|------------|--------|-------|----------|
| 19 | 52.00 | 71.00 | 5191.00 | 29.00 | 68.00 | 4477.00 | 53.00 | 60.00 | 753.00 |
| 0 | 53.00 | 150.00 | 7300.00 | 53.00 | 105.00 | 7730.00 | 53.00 | 64.00 | 2067.00 |
| -20 | 33.00 | 159.00 | 98492.00 | 53.00 | 149.00 | 9608.00 | 53.00 | 91.00 | 5349.00 |
----------------------------------------------------------------------------------------------------------
o NPS4
----------------------------------------------------------------------------------------------------------
| Hackbench | Cyclictest LN = 19 | Cyclictest LN = 0 | Cyclictest LN = -20 |
| LN |------------------------------|-------------------------------|---------------------------|
| | Min | Avg | Max | Min | Avg | Max | Min | Avg | Max |
|-------------|--------|---------|-----------|--------|---------|------------|--------|-------|----------|
| 19 | 53.00 | 84.00 | 4790.00 | 53.00 | 72.00 | 3456.00 | 53.00 | 58.00 | 1271.00 |
| 0 | 53.00 | 99.00 | 5494.00 | 52.00 | 74.00 | 5813.00 | 53.00 | 59.00 | 1004.00 |
| -20 | 45.00 | 84.00 | 3592.00 | 53.00 | 91.00 | 15222.00 | 53.00 | 74.00 | 5232.00 | ^
----------------------------------------------------------------------------------------------------------
- Hackbench: 128 Groups
perf bench sched messaging -p -l 500000 -g 128&
cyclictest --policy other -D 5 -q -n -h 2000
o NPS1
----------------------------------------------------------------------------------------------------------
| Hackbench | Cyclictest LN = 19 | Cyclictest LN = 0 | Cyclictest LN = -20 |
| LN |------------------------------|-------------------------------|---------------------------|
| | Min | Avg | Max | Min | Avg | Max | Min | Avg | Max |
|-------------|--------|---------|-----------|--------|---------|------------|--------|-------|----------|
| 19 | 53.00 | 274.00 | 11294.00 | 33.00 | 130.00 | 20071.00 | 53.00 | 56.00 | 244.00 | ^
| 0 | 53.00 | 125.00 | 10014.00 | 53.00 | 113.00 | 15857.00 | 53.00 | 57.00 | 250.00 |
| -20 | 53.00 | 187.00 | 49565.00 | 53.00 | 230.00 | 73353.00 | 53.00 | 118.00| 8816.00 |
----------------------------------------------------------------------------------------------------------
o NPS4
----------------------------------------------------------------------------------------------------------
| Hackbench | Cyclictest LN = 19 | Cyclictest LN = 0 | Cyclictest LN = -20 |
| LN |------------------------------|-------------------------------|---------------------------|
| | Min | Avg | Max | Min | Avg | Max | Min | Avg | Max |
|-------------|--------|---------|-----------|--------|---------|------------|--------|-------|----------|
| 19 | 53.00 | 271.00 | 11411.00 | 53.00 | 82.00 | 5486.00 | 25.00 | 57.00 | 1256.00 |
| 0 | 53.00 | 148.00 | 8374.00 | 52.00 | 109.00 | 11074.00 | 52.00 | 59.00 | 1068.00 |
| -20 | 53.00 | 202.00 | 52537.00 | 53.00 | 205.00 | 22265.00 | 52.00 | 87.00 | 14151.00 |
----------------------------------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ Hackbench + schbench - Various Latency Nice Values ~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
perf bench sched messaging -p -l 400000 -g 128
schbench -m 2 -t 1 -s 30
o NPS1
-------------------------------------------------------------------------------------------------
| Hackbench | schbench LN = 19 | schbench LN = 0 | schbench LN = -20 |
| LN |----------------------------|---------------------------|--------------------------|
| | 90th | 95th | 99th | 90th | 95th | 99th | 90th | 95th | 99th |
|-----------|--------|--------|----------|--------|--------|---------|--------|--------|--------|
| 19 | 38 | 131 | 1458 | 46 | 151 | 2636 | 11 | 19 | 410 | ^
| 0 | 45 | 98 | 1758 | 25 | 50 | 1670 | 16 | 30 | 1042 |
| -20 | 47 | 348 | 29280 | 40 | 109 | 16144 | 35 | 63 | 9104 |
-------------------------------------------------------------------------------------------------
o NPS4
-------------------------------------------------------------------------------------------------
| Hackbench | schbench LN = 19 | schbench LN = 0 | schbench LN = -20 |
| LN |----------------------------|---------------------------|--------------------------|
| | 90th | 95th | 99th | 90th | 95th | 99th | 90th | 95th | 99th |
|-----------|--------|--------|----------|--------|--------|---------|--------|--------|--------|
| 19 | 19 | 60 | 1886 | 17 | 29 | 621 | 10 | 18 | 227 |
| 0 | 51 | 141 | 8120 | 37 | 78 | 8880 | 33 | 55 | 474 | ^
| -20 | 48 | 1494 | 27296 | 51 | 469 | 40384 | 31 | 64 | 4092 | ^
-------------------------------------------------------------------------------------------------
^ Note: There are cases where the Max, 99th percentile latency is
non-monotonic but I've also seen a good amount of run to run variation
there with a single bad sample polluting the results. In such cases,
the averages are more representative.
>
> [1] https://source.android.com/docs/core/debug/eval_perf#touchlatency
>
> [..snip..]
>
Apart from couple of anomalies, latency nice reduces wait time, especially
when the system is heavily loaded. If there is any data, or any specific
workload you would like me to run on the test system, please do let me know.
Meanwhile, I'll try to get some numbers for larger workloads like SpecJBB
that did see improvements with latency nice on v5.
--
Thanks and Regards,
Prateek
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