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Message-ID: <ZAX/OOm4IP41NcHY@vingu-book>
Date: Mon, 6 Mar 2023 15:56:56 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>
Cc: qyousef@...alina.io, chris.hyser@...cle.com,
patrick.bellasi@...bug.net, David.Laight@...lab.com,
pjt@...gle.com, pavel@....cz, qperret@...gle.com,
tim.c.chen@...ux.intel.com, joshdon@...gle.com, timj@....org,
kprateek.nayak@....com, yu.c.chen@...el.com,
youssefesmat@...omium.org, joel@...lfernandes.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, tj@...nel.org,
lizefan.x@...edance.com, hannes@...xchg.org,
cgroups@...r.kernel.org, corbet@....net, linux-doc@...r.kernel.org
Subject: Re: [PATCH v12 8/8] sched/fair: Add latency list
Le lundi 06 mars 2023 à 17:03:30 (+0530), Shrikanth Hegde a écrit :
>
>
> On 3/5/23 6:33 PM, Vincent Guittot wrote:
> > On Sat, 4 Mar 2023 at 16:13, Shrikanth Hegde <sshegde@...ux.vnet.ibm.com> wrote:
> >>
> >>
> >> On 3/3/23 10:01 PM, Vincent Guittot wrote:
> >>> Le jeudi 02 mars 2023 à 23:37:52 (+0530), Shrikanth Hegde a écrit :
> >>>> On 3/2/23 8:30 PM, Shrikanth Hegde wrote:
> >>>>> On 3/2/23 6:47 PM, Vincent Guittot wrote:
> >>>>>> On Thu, 2 Mar 2023 at 12:00, Shrikanth Hegde <sshegde@...ux.vnet.ibm.com> wrote:
> >>>>>>> On 3/2/23 1:20 PM, Vincent Guittot wrote:
> >>>>>>>> On Wed, 1 Mar 2023 at 19:48, shrikanth hegde <sshegde@...ux.vnet.ibm.com> wrote:
> >>>>>>>>> On 2/24/23 3:04 PM, Vincent Guittot wrote:
> >>> [...]
> >>>
> >>>>>>>>> Ran the schbench and hackbench with this patch series. Here comparison is
> >>>>>>>>> between 6.2 stable tree, 6.2 + Patch and 6.2 + patch + above re-arrange of
> >>>>>>>>> latency_node. Ran two cgroups, in one cgroup running stress-ng at 50%(group1)
> >>>>>>>>> and other is running these benchmarks (group2). Set the latency nice
> >>>>>>>>> of group2 to -20. These are run on Power system with 12 cores with SMT=8.
> >>>>>>>>> Total of 96 CPU.
> >>>>>>>>>
> >>>>>>>>> schbench gets lower latency compared to stabletree. Whereas hackbench seems
> >>>>>>>>> to regress under this case. Maybe i am doing something wrong. I will re-run
> >>>>>>>>> and attach the numbers to series.
> >>>>>>>>> Please suggest if any variation in the test i need to try.
> >>>>>>>> hackbench takes advanatge of a latency nice 19 as it mainly wants to
> >>>>>>>> run longer slice to move forward rather than preempting others all the
> >>>>>>>> time
> >>>>>>> hackbench still seems to regress in different latency nice values compared to
> >>>>>>> baseline of 6.2 in this case. up to 50% in some cases.
> >>>>>>>
> >>>>>>> 12 core powerpc system with SMT=8 i.e 96 CPU
> >>>>>>> running 2 CPU cgroups. No quota assigned.
> >>>>>>> 1st cgroup is running stress-ng with 48 threads. Consuming 50% of CPU.
> >>>>>>> latency is not changed for this cgroup.
> >>>>>>> 2nd cgroup is running hackbench. This cgroup is assigned the different latency
> >>>>>>> nice values of 0, -20 and 19.
> >>>>>> According to your other emails, you are using the cgroup interface and
> >>>>>> not the task's one. Do I get it right ?
> >>>>> right. I create cgroup, attach bash command with echo $$,
> >>>>> assign the latency nice to cgroup, and run hackbench from that bash prompt.
> >>>>>
> >>>>>> I haven't run test such tests in a cgroup but at least the test with
> >>>>>> latency_nice == 0 should not make any noticeable difference. Does this
> >>>>>> include the re-arrange patch that you have proposed previously ?
> >>>>> No. This is only with V12 of the series.
> >>>>>
> >>>>>> Also, the tests that you did on v6, gave better result.
> >>>>>> https://lore.kernel.org/lkml/34112324-de67-55eb-92bc-181a98c4311c@linux.vnet.ibm.com/
> >>>>>>
> >>>>>> Are you running same tests or you changed something in the mean time ?
> >>>>> Test machine got changed.
> >>>>> now i re-read my earlier mail. I see it was slightly different.
> >>>>> I had created only one cgroup and stress-ng was run
> >>>>> without any cgroup. Let me try that scenario and get the numbers.
> >>>> Tried the same method of testing i had done on V7 of the series. on this
> >>>> machine hackbench still regress's both on V12 as well as V7 of the series.
> >>>>
> >>>> Created one cpu cgroup called cgroup1. created two bash prompts.
> >>>> assigned "bash $$" to cgroup1 and on other bash prompt running,
> >>>> stress-ng --cpu=96 -l 50. Ran hackbench from cgroup1 prompt.
> >>>> assigned latency values to the cgroup1.
> >>> I have tried to reproduce your results on some of my systems but I can't see
> >>> the impacts that you are reporting below.
> >>> The fact that your other platform was not impacted as well could imply that
> >>> it's specific to this platform.
> >>> In particular, the lat nice=0 case should not show any real impact as it
> >>> should be similar to a nop. At least that what I can see in the tests on my
> >>> platforms and Prateek on his.
> >>>
> >>> Nevertheless, could you try to run your tests with the changes below ?
> >>> These are the only places which could have an impact even with lat nice = 0
> >>>
> >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >>> index 8137bca80572..979571a98b28 100644
> >>> --- a/kernel/sched/fair.c
> >>> +++ b/kernel/sched/fair.c
> >>> @@ -4991,8 +4991,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> >>> if (delta < offset)
> >>> return;
> >>>
> >>> - if ((delta > ideal_runtime) ||
> >>> - (delta > get_latency_max()))
> >>> + if (delta > ideal_runtime)
> >>> resched_curr(rq_of(cfs_rq));
> >>> }
> >>>
> >>> @@ -7574,9 +7573,10 @@ static long wakeup_latency_gran(struct sched_entity *curr, struct sched_entity *
> >>> * Otherwise, use the latency weight to evaluate how much scheduling
> >>> * delay is acceptable by se.
> >>> */
> >>> - if ((latency_offset < 0) || (curr->latency_offset < 0))
> >>> + if ((latency_offset < 0) || (curr->latency_offset < 0)) {
> >>> latency_offset -= curr->latency_offset;
> >>> - latency_offset = min_t(long, latency_offset, get_latency_max());
> >>> + latency_offset = min_t(long, latency_offset, get_latency_max());
> >>> + }
> >>>
> >>> return latency_offset;
> >>> }
> >>> @@ -7635,7 +7635,6 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
> >>> * for low priority task. Make sure that long sleeping task will get a
> >>> * chance to preempt current.
> >>> */
> >>> - gran = min_t(s64, gran, get_latency_max());
> >>>
> >>> if (vdiff > gran)
> >>> return 1;
> >>>
> >> Above patch helps. thank you.
> > Great. At least we have narrow the problem to one f the 3 changes.
> >
> >> Numbers are comparable to 6.2 and there is slight improvement. Much better than V12 numbers.
> >>
> >> type groups | v6.2 |v6.2 + V12| v6.2 + V12 | v6.2 + V12
> >> | |lat nice=0| lat nice=-20| lat nice=+19
> >>
> >> Process 10 | 0.33 | 0.37 | 0.38 | 0.37
> >> Process 20 | 0.61 | 0.67 | 0.68 | 0.67
> >> Process 30 | 0.85 | 0.95 | 0.95 | 0.96
> >> Process 40 | 1.10 | 1.20 | 1.20 | 1.21
> >> Process 50 | 1.34 | 1.47 | 1.44 | 1.45
> >> Process 60 | 1.57 | 1.70 | 1.71 | 1.70
> >> thread 10 | 0.36 | 0.40 | 0.39 | 0.39
> >> thread 20 | 0.65 | 0.72 | 0.71 | 0.71
> >> Process(Pipe) 10 | 0.18 | 0.31 | 0.31 | 0.33
> >> Process(Pipe) 20 | 0.32 | 0.51 | 0.50 | 0.50
> >> Process(Pipe) 30 | 0.43 | 0.65 | 0.67 | 0.67
> >> Process(Pipe) 40 | 0.57 | 0.82 | 0.83 | 0.83
> >> Process(Pipe) 50 | 0.67 | 1.00 | 0.97 | 0.98
> >> Process(Pipe) 60 | 0.81 | 1.13 | 1.11 | 1.12
> >> thread(Pipe) 10 | 0.19 | 0.33 | 0.33 | 0.33
> >> thread(Pipe) 20 | 0.34 | 0.53 | 0.51 | 0.52
> >>
> >>
> >>
> >> type groups | v6.2 |v6.2+ V12+ | v6.2 + V12+| v6.2 + V12
> >> | |above patch|above patch | above patch
> >> | |lat nice=0 |lat nice=-20| lat nice=+19
> >>
> >> Process 10 | 0.36 | 0.33 | 0.34 | 0.34
> >> Process 20 | 0.62 | 0.60 | 0.61 | 0.61
> >> Process 30 | 0.87 | 0.84 | 0.85 | 0.84
> >> Process 40 | 1.13 | 1.09 | 1.10 | 1.09
> >> Process 50 | 1.38 | 1.33 | 1.33 | 1.34
> >> Process 60 | 1.64 | 1.56 | 1.58 | 1.56
> >> thread 10 | 0.35 | 0.35 | 0.35 | 0.35
> >> thread 20 | 0.64 | 0.63 | 0.63 | 0.63
> >> Process(Pipe) 10 | 0.20 | 0.18 | 0.18 | 0.18
> >> Process(Pipe) 20 | 0.32 | 0.31 | 0.31 | 0.32
> >> Process(Pipe) 30 | 0.44 | 0.43 | 0.43 | 0.43
> >> Process(Pipe) 40 | 0.56 | 0.57 | 0.56 | 0.55
> >> Process(Pipe) 50 | 0.70 | 0.67 | 0.67 | 0.67
> >> Process(Pipe) 60 | 0.83 | 0.79 | 0.81 | 0.80
> >> thread(Pipe) 10 | 0.21 | 0.19 | 0.19 | 0.19
> >> thread(Pipe) 20 | 0.35 | 0.33 | 0.34 | 0.33
> >>
> >>
> >> Do you want me to try any other experiment on this further?
> > Yes, would be good to know which of the 3 changes in the patch create
> > the regression
> >
> > I suspect the 1st change to be the root cause of your problem but It
> > would be good if you can confirm my assumption with some tests
> >
> > Thanks
>
> Applied each change individually. 3rd change seems to cause the regression.
> Kept only the 3rd change and numbers are same as stable 6.2 for latency nice
> value of 0.
Ok, it's the patch 1 that aims to prevent some unfairness with low weight
waking task. And your platform probably falls in the last part of the commit:
" Strictly speaking, we should use cfs->min_vruntime instead of
curr->vruntime but it doesn't worth the additional overhead and complexity
as the vruntime of current should be close to min_vruntime if not equal."
Could you try the patch below on top of v12 ?
---
kernel/sched/fair.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e2aeb4511686..77b03a280912 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5049,7 +5049,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
}
static int
-wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se, struct cfs_rq *cfs_rq);
/*
* Pick the next process, keeping these things in mind, in this order:
@@ -5088,16 +5088,16 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
second = curr;
}
- if (second && wakeup_preempt_entity(second, left) < 1)
+ if (second && wakeup_preempt_entity(second, left, cfs_rq) < 1)
se = second;
}
- if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) {
+ if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left, cfs_rq) < 1) {
/*
* Someone really wants this to run. If it's not unfair, run it.
*/
se = cfs_rq->next;
- } else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) {
+ } else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left, cfs_rq) < 1) {
/*
* Prefer last buddy, try to return the CPU to a preempted task.
*/
@@ -5107,7 +5107,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
/* Check for latency sensitive entity waiting for running */
latency = __pick_first_latency(cfs_rq);
if (latency && (latency != se) &&
- wakeup_preempt_entity(latency, se) < 1)
+ wakeup_preempt_entity(latency, se, cfs_rq) < 1)
se = latency;
return se;
@@ -7808,7 +7808,7 @@ static unsigned long wakeup_gran(struct sched_entity *se)
*
*/
static int
-wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se, struct cfs_rq *cfs_rq)
{
s64 gran, vdiff = curr->vruntime - se->vruntime;
s64 offset = wakeup_latency_gran(curr, se);
@@ -7818,6 +7818,8 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
gran = offset + wakeup_gran(se);
+ if (vdiff > gran)
+ return 1;
/*
* At wake up, the vruntime of a task is capped to not be older than
* a sched_latency period compared to min_vruntime. This prevents long
@@ -7827,9 +7829,8 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
* for low priority task. Make sure that long sleeping task will get a
* chance to preempt current.
*/
- gran = min_t(s64, gran, get_latency_max());
-
- if (vdiff > gran)
+ vdiff = cfs_rq->min_vruntime - se->vruntime;
+ if (vdiff > get_latency_max())
return 1;
return 0;
@@ -7933,7 +7934,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;
update_curr(cfs_rq_of(se));
- if (wakeup_preempt_entity(se, pse) == 1) {
+ if (wakeup_preempt_entity(se, pse, cfs_rq_of(se)) == 1) {
/*
* Bias pick_next to pick the sched entity that is
* triggering this preemption.
--
2.34.1
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index cdcd991bbcf1..c89c201dd164 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7827,7 +7827,6 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
> * for low priority task. Make sure that long sleeping task will get a
> * chance to preempt current.
> */
> - gran = min_t(s64, gran, get_latency_max());
>
> if (vdiff > gran)
> return 1;
>
>
>
> >>>> I will try to run with only task's set with latency_nice=0 as well.
> >>>>
> >>>> type groups | v6.2 |v6.2 + V12| v6.2 + V12 | v6.2 + V12
> >>>> | |lat nice=0| lat nice=-20| lat nice=+19
> >>>>
> >>>> Process 10 | 0.33 | 0.37 | 0.38 | 0.37
> >>>> Process 20 | 0.61 | 0.67 | 0.68 | 0.67
> >>>> Process 30 | 0.85 | 0.95 | 0.95 | 0.96
> >>>> Process 40 | 1.10 | 1.20 | 1.20 | 1.21
> >>>> Process 50 | 1.34 | 1.47 | 1.44 | 1.45
> >>>> Process 60 | 1.57 | 1.70 | 1.71 | 1.70
> >>>> thread 10 | 0.36 | 0.40 | 0.39 | 0.39
> >>>> thread 20 | 0.65 | 0.72 | 0.71 | 0.71
> >>>> Process(Pipe) 10 | 0.18 | 0.31 | 0.31 | 0.33
> >>>> Process(Pipe) 20 | 0.32 | 0.51 | 0.50 | 0.50
> >>>> Process(Pipe) 30 | 0.43 | 0.65 | 0.67 | 0.67
> >>>> Process(Pipe) 40 | 0.57 | 0.82 | 0.83 | 0.83
> >>>> Process(Pipe) 50 | 0.67 | 1.00 | 0.97 | 0.98
> >>>> Process(Pipe) 60 | 0.81 | 1.13 | 1.11 | 1.12
> >>>> thread(Pipe) 10 | 0.19 | 0.33 | 0.33 | 0.33
> >>>> thread(Pipe) 20 | 0.34 | 0.53 | 0.51 | 0.52
> >>>>
> >>>>
> >>>>
> >>>> type groups | v6.2 |v6.2 + V7 | v6.2 + V7 | v6.2 + V7
> >>>> | |lat nice=0|lat nice=-20| lat nice=+19
> >>>> Process 10 | 0.33 | 0.37 | 0.37 | 0.37
> >>>> Process 20 | 0.61 | 0.67 | 0.67 | 0.67
> >>>> Process 30 | 0.85 | 0.96 | 0.94 | 0.95
> >>>> Process 40 | 1.10 | 1.20 | 1.20 | 1.20
> >>>> Process 50 | 1.34 | 1.45 | 1.46 | 1.45
> >>>> Process 60 | 1.57 | 1.71 | 1.68 | 1.72
> >>>> thread 10 | 0.36 | 0.40 | 0.40 | 0.40
> >>>> thread 20 | 0.65 | 0.71 | 0.71 | 0.71
> >>>> Process(Pipe) 10 | 0.18 | 0.30 | 0.30 | 0.31
> >>>> Process(Pipe) 20 | 0.32 | 0.50 | 0.50 | 0.50
> >>>> Process(Pipe) 30 | 0.43 | 0.67 | 0.67 | 0.66
> >>>> Process(Pipe) 40 | 0.57 | 0.86 | 0.84 | 0.84
> >>>> Process(Pipe) 50 | 0.67 | 0.99 | 0.97 | 0.97
> >>>> Process(Pipe) 60 | 0.81 | 1.10 | 1.13 | 1.13
> >>>> thread(Pipe) 10 | 0.19 | 0.34 | 0.34 | 0.33
> >>>> thread(Pipe) 20 | 0.34 | 0.55 | 0.53 | 0.54
> >>>>
> >>>>>>> Numbers are average of 10 runs in each case. Time is in seconds
> >>>>>>>
> >>>>>>> type groups | v6.2 | v6.2 + V12 | v6.2 + V12 | v6.2 + V12
> >>>>>>> | | lat nice=0 | lat nice=-20| lat nice=+19
> >>>>>>> | | | |
> >>>>>>> Process 10 | 0.36 | 0.41 | 0.43 | 0.42
> >>>>>>> Process 20 | 0.62 | 0.76 | 0.75 | 0.75
> >>>>>>> Process 30 | 0.87 | 1.05 | 1.04 | 1.06
> >>>>>>> Process 40 | 1.13 | 1.34 | 1.33 | 1.33
> >>>>>>> Process 50 | 1.38 | 1.62 | 1.66 | 1.63
> >>>>>>> Process 60 | 1.64 | 1.91 | 1.97 | 1.90
> >>>>>>> thread 10 | 0.35 | 0.41 | 0.44 | 0.42
> >>>>>>> thread 20 | 0.64 | 0.78 | 0.77 | 0.79
> >>>>>>> Process(Pipe) 10 | 0.20 | 0.34 | 0.33 | 0.34
> >>>>>>> Process(Pipe) 20 | 0.32 | 0.52 | 0.53 | 0.52
> >>>>>>> Process(Pipe) 30 | 0.44 | 0.70 | 0.70 | 0.69
> >>>>>>> Process(Pipe) 40 | 0.56 | 0.88 | 0.89 | 0.88
> >>>>>>> Process(Pipe) 50 | 0.70 | 1.08 | 1.08 | 1.07
> >>>>>>> Process(Pipe) 60 | 0.83 | 1.27 | 1.27 | 1.26
> >>>>>>> thread(Pipe) 10 | 0.21 | 0.35 | 0.34 | 0.36
> >>>>>>> thread(Pipe) 10 | 0.35 | 0.55 | 0.58 | 0.55
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>>> Re-arrange seems to help the patch series by avoiding an cacheline miss.
> >>>>>>>>>
> >>>>>>>>> =========================
> >>>>>>>>> schbench
> >>>>>>>>> =========================
> >>>>>>>>> 6.2 | 6.2 + V12 | 6.2 + V12 + re-arrange
> >>>>>>>>> 1 Thread
> >>>>>>>>> 50.0th: 9.00 | 9.00 | 9.50
> >>>>>>>>> 75.0th: 10.50 | 10.00 | 9.50
> >>>>>>>>> 90.0th: 11.00 | 11.00 | 10.50
> >>>>>>>>> 95.0th: 11.00 | 11.00 | 11.00
> >>>>>>>>> 99.0th: 11.50 | 11.50 | 11.50
> >>>>>>>>> 99.5th: 12.50 | 12.00 | 12.00
> >>>>>>>>> 99.9th: 14.50 | 13.50 | 12.00
> >>>>>>>>> 2 Threads
> >>>>>>>>> 50.0th: 9.50 | 9.50 | 8.50
> >>>>>>>>> 75.0th: 11.00 | 10.50 | 9.50
> >>>>>>>>> 90.0th: 13.50 | 11.50 | 10.50
> >>>>>>>>> 95.0th: 14.00 | 12.00 | 11.00
> >>>>>>>>> 99.0th: 15.50 | 13.50 | 12.00
> >>>>>>>>> 99.5th: 16.00 | 14.00 | 12.00
> >>>>>>>>> 99.9th: 17.00 | 16.00 | 16.50
> >>>>>>>>> 4 Threads
> >>>>>>>>> 50.0th: 11.50 | 11.50 | 10.50
> >>>>>>>>> 75.0th: 13.50 | 12.50 | 12.50
> >>>>>>>>> 90.0th: 15.50 | 14.50 | 14.00
> >>>>>>>>> 95.0th: 16.50 | 15.50 | 14.50
> >>>>>>>>> 99.0th: 20.00 | 17.50 | 16.50
> >>>>>>>>> 99.5th: 20.50 | 18.50 | 17.00
> >>>>>>>>> 99.9th: 22.50 | 21.00 | 19.00
> >>>>>>>>> 8 Threads
> >>>>>>>>> 50.0th: 14.00 | 14.00 | 14.00
> >>>>>>>>> 75.0th: 16.00 | 16.00 | 16.00
> >>>>>>>>> 90.0th: 18.00 | 18.00 | 17.50
> >>>>>>>>> 95.0th: 18.50 | 18.50 | 18.50
> >>>>>>>>> 99.0th: 20.00 | 20.00 | 20.00
> >>>>>>>>> 99.5th: 20.50 | 21.50 | 21.00
> >>>>>>>>> 99.9th: 22.50 | 23.50 | 23.00
> >>>>>>>>> 16 Threads
> >>>>>>>>> 50.0th: 19.00 | 18.50 | 19.00
> >>>>>>>>> 75.0th: 23.00 | 22.50 | 23.00
> >>>>>>>>> 90.0th: 25.00 | 25.50 | 25.00
> >>>>>>>>> 95.0th: 26.50 | 26.50 | 26.00
> >>>>>>>>> 99.0th: 28.50 | 29.00 | 28.50
> >>>>>>>>> 99.5th: 31.00 | 30.00 | 30.00
> >>>>>>>>> 99.9th: 5626.00 | 4761.50 | 32.50
> >>>>>>>>> 32 Threads
> >>>>>>>>> 50.0th: 27.00 | 27.50 | 29.00
> >>>>>>>>> 75.0th: 35.50 | 36.50 | 38.50
> >>>>>>>>> 90.0th: 42.00 | 44.00 | 50.50
> >>>>>>>>> 95.0th: 447.50 | 2959.00 | 8544.00
> >>>>>>>>> 99.0th: 7372.00 | 17032.00 | 19136.00
> >>>>>>>>> 99.5th: 15360.00 | 19808.00 | 20704.00
> >>>>>>>>> 99.9th: 20640.00 | 30048.00 | 30048.00
> >>>>>>>>>
> >>>>>>>>> ====================
> >>>>>>>>> hackbench
> >>>>>>>>> ====================
> >>>>>>>>> 6.2 | 6.2 + V12 | 6.2+ V12 +re-arrange
> >>>>>>>>>
> >>>>>>>>> Process 10 Time: 0.35 | 0.42 | 0.41
> >>>>>>>>> Process 20 Time: 0.61 | 0.76 | 0.76
> >>>>>>>>> Process 30 Time: 0.87 | 1.06 | 1.05
> >>>>>>>>> thread 10 Time: 0.35 | 0.43 | 0.42
> >>>>>>>>> thread 20 Time: 0.66 | 0.79 | 0.78
> >>>>>>>>> Process(Pipe) 10 Time: 0.21 | 0.33 | 0.32
> >>>>>>>>> Process(Pipe) 20 Time: 0.34 | 0.52 | 0.52
> >>>>>>>>> Process(Pipe) 30 Time: 0.46 | 0.72 | 0.71
> >>>>>>>>> thread(Pipe) 10 Time: 0.21 | 0.34 | 0.34
> >>>>>>>>> thread(Pipe) 20 Time: 0.36 | 0.56 | 0.56
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>> struct list_head group_node;
> >>>>>>>>>> unsigned int on_rq;
> >>>>>>>>>>
> >>>>>>>>>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> >>>>>>>>>> index 093cc1af73dc..752fd364216c 100644
> >>>>>>>>>> --- a/kernel/sched/core.c
> >>>>>>>>>> +++ b/kernel/sched/core.c
> >>>>>>>>>> @@ -4434,6 +4434,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
> >>>>>>>>>> p->se.nr_migrations = 0;
> >>>>>>>>>> p->se.vruntime = 0;
> >>>>>>>>>> INIT_LIST_HEAD(&p->se.group_node);
> >>>>>>>>>> + RB_CLEAR_NODE(&p->se.latency_node);
> >>>>>>>>>>
> >>>>>>>>>> #ifdef CONFIG_FAIR_GROUP_SCHED
> >>>>>>>>>> p->se.cfs_rq = NULL;
> >>>>>>>>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >>>>>>>>>> index 125a6ff53378..e2aeb4511686 100644
> >>>>>>>>>> --- a/kernel/sched/fair.c
> >>>>>>>>>> +++ b/kernel/sched/fair.c
> >>>>>>>>>> @@ -680,7 +680,85 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
> >>>>>>>>>>
> >>>>>>>>>> return __node_2_se(last);
> >>>>>>>>>> }
> >>>>>>>>>> +#endif
> >>>>>>>>>>
> >>>>>>>>>> +/**************************************************************
> >>>>>>>>>> + * Scheduling class tree data structure manipulation methods:
> >>>>>>>>>> + * for latency
> >>>>>>>>>> + */
> >>>>>>>>>> +
> >>>>>>>>>> +static inline bool latency_before(struct sched_entity *a,
> >>>>>>>>>> + struct sched_entity *b)
> >>>>>>>>>> +{
> >>>>>>>>>> + return (s64)(a->vruntime + a->latency_offset - b->vruntime - b->latency_offset) < 0;
> >>>>>>>>>> +}
> >>>>>>>>>> +
> >>>>>>>>>> +#define __latency_node_2_se(node) \
> >>>>>>>>>> + rb_entry((node), struct sched_entity, latency_node)
> >>>>>>>>>> +
> >>>>>>>>>> +static inline bool __latency_less(struct rb_node *a, const struct rb_node *b)
> >>>>>>>>>> +{
> >>>>>>>>>> + return latency_before(__latency_node_2_se(a), __latency_node_2_se(b));
> >>>>>>>>>> +}
> >>>>>>>>>> +
> >>>>>>>>>> +/*
> >>>>>>>>>> + * Enqueue an entity into the latency rb-tree:
> >>>>>>>>>> + */
> >>>>>>>>>> +static void __enqueue_latency(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> >>>>>>>>>> +{
> >>>>>>>>>> +
> >>>>>>>>>> + /* Only latency sensitive entity can be added to the list */
> >>>>>>>>>> + if (se->latency_offset >= 0)
> >>>>>>>>>> + return;
> >>>>>>>>>> +
> >>>>>>>>>> + if (!RB_EMPTY_NODE(&se->latency_node))
> >>>>>>>>>> + return;
> >>>>>>>>>> +
> >>>>>>>>>> + /*
> >>>>>>>>>> + * The entity is always added the latency list at wakeup.
> >>>>>>>>>> + * Then, a not waking up entity that is put back in the list after an
> >>>>>>>>>> + * execution time less than sysctl_sched_min_granularity, means that
> >>>>>>>>>> + * the entity has been preempted by a higher sched class or an entity
> >>>>>>>>>> + * with higher latency constraint. In thi case, the entity is also put
> >>>>>>>>>> + * back in the latency list so it gets a chance to run 1st during the
> >>>>>>>>>> + * next slice.
> >>>>>>>>>> + */
> >>>>>>>>>> + if (!(flags & ENQUEUE_WAKEUP)) {
> >>>>>>>>>> + u64 delta_exec = se->sum_exec_runtime - se->prev_sum_exec_runtime;
> >>>>>>>>>> +
> >>>>>>>>>> + if (delta_exec >= sysctl_sched_min_granularity)
> >>>>>>>>>> + return;
> >>>>>>>>>> + }
> >>>>>>>>>> +
> >>>>>>>>>> + rb_add_cached(&se->latency_node, &cfs_rq->latency_timeline, __latency_less);
> >>>>>>>>>> +}
> >>>>>>>>>> +
> >>>>>>>>>> +/*
> >>>>>>>>>> + * Dequeue an entity from the latency rb-tree and return true if it was really
> >>>>>>>>>> + * part of the rb-tree:
> >>>>>>>>>> + */
> >>>>>>>>>> +static bool __dequeue_latency(struct cfs_rq *cfs_rq, struct sched_entity *se)
> >>>>>>>>>> +{
> >>>>>>>>>> + if (!RB_EMPTY_NODE(&se->latency_node)) {
> >>>>>>>>>> + rb_erase_cached(&se->latency_node, &cfs_rq->latency_timeline);
> >>>>>>>>>> + RB_CLEAR_NODE(&se->latency_node);
> >>>>>>>>>> + return true;
> >>>>>>>>>> + }
> >>>>>>>>>> +
> >>>>>>>>>> + return false;
> >>>>>>>>>> +}
> >>>>>>>>>> +
> >>>>>>>>>> +static struct sched_entity *__pick_first_latency(struct cfs_rq *cfs_rq)
> >>>>>>>>>> +{
> >>>>>>>>>> + struct rb_node *left = rb_first_cached(&cfs_rq->latency_timeline);
> >>>>>>>>>> +
> >>>>>>>>>> + if (!left)
> >>>>>>>>>> + return NULL;
> >>>>>>>>>> +
> >>>>>>>>>> + return __latency_node_2_se(left);
> >>>>>>>>>> +}
> >>>>>>>>>> +
> >>>>>>>>>> +#ifdef CONFIG_SCHED_DEBUG
> >>>>>>>>>> /**************************************************************
> >>>>>>>>>> * Scheduling class statistics methods:
> >>>>>>>>>> */
> >>>>>>>>>> @@ -4758,8 +4836,10 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> >>>>>>>>>> check_schedstat_required();
> >>>>>>>>>> update_stats_enqueue_fair(cfs_rq, se, flags);
> >>>>>>>>>> check_spread(cfs_rq, se);
> >>>>>>>>>> - if (!curr)
> >>>>>>>>>> + if (!curr) {
> >>>>>>>>>> __enqueue_entity(cfs_rq, se);
> >>>>>>>>>> + __enqueue_latency(cfs_rq, se, flags);
> >>>>>>>>>> + }
> >>>>>>>>>> se->on_rq = 1;
> >>>>>>>>>>
> >>>>>>>>>> if (cfs_rq->nr_running == 1) {
> >>>>>>>>>> @@ -4845,8 +4925,10 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> >>>>>>>>>>
> >>>>>>>>>> clear_buddies(cfs_rq, se);
> >>>>>>>>>>
> >>>>>>>>>> - if (se != cfs_rq->curr)
> >>>>>>>>>> + if (se != cfs_rq->curr) {
> >>>>>>>>>> __dequeue_entity(cfs_rq, se);
> >>>>>>>>>> + __dequeue_latency(cfs_rq, se);
> >>>>>>>>>> + }
> >>>>>>>>>> se->on_rq = 0;
> >>>>>>>>>> account_entity_dequeue(cfs_rq, se);
> >>>>>>>>>>
> >>>>>>>>>> @@ -4941,6 +5023,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
> >>>>>>>>>> */
> >>>>>>>>>> update_stats_wait_end_fair(cfs_rq, se);
> >>>>>>>>>> __dequeue_entity(cfs_rq, se);
> >>>>>>>>>> + __dequeue_latency(cfs_rq, se);
> >>>>>>>>>> update_load_avg(cfs_rq, se, UPDATE_TG);
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> @@ -4979,7 +5062,7 @@ static struct sched_entity *
> >>>>>>>>>> pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> >>>>>>>>>> {
> >>>>>>>>>> struct sched_entity *left = __pick_first_entity(cfs_rq);
> >>>>>>>>>> - struct sched_entity *se;
> >>>>>>>>>> + struct sched_entity *latency, *se;
> >>>>>>>>>>
> >>>>>>>>>> /*
> >>>>>>>>>> * If curr is set we have to see if its left of the leftmost entity
> >>>>>>>>>> @@ -5021,6 +5104,12 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> >>>>>>>>>> se = cfs_rq->last;
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> + /* Check for latency sensitive entity waiting for running */
> >>>>>>>>>> + latency = __pick_first_latency(cfs_rq);
> >>>>>>>>>> + if (latency && (latency != se) &&
> >>>>>>>>>> + wakeup_preempt_entity(latency, se) < 1)
> >>>>>>>>>> + se = latency;
> >>>>>>>>>> +
> >>>>>>>>>> return se;
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> @@ -5044,6 +5133,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
> >>>>>>>>>> update_stats_wait_start_fair(cfs_rq, prev);
> >>>>>>>>>> /* Put 'current' back into the tree. */
> >>>>>>>>>> __enqueue_entity(cfs_rq, prev);
> >>>>>>>>>> + __enqueue_latency(cfs_rq, prev, 0);
> >>>>>>>>>> /* in !on_rq case, update occurred at dequeue */
> >>>>>>>>>> update_load_avg(cfs_rq, prev, 0);
> >>>>>>>>>> }
> >>>>>>>>>> @@ -12222,6 +12312,7 @@ static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
> >>>>>>>>>> void init_cfs_rq(struct cfs_rq *cfs_rq)
> >>>>>>>>>> {
> >>>>>>>>>> cfs_rq->tasks_timeline = RB_ROOT_CACHED;
> >>>>>>>>>> + cfs_rq->latency_timeline = RB_ROOT_CACHED;
> >>>>>>>>>> u64_u32_store(cfs_rq->min_vruntime, (u64)(-(1LL << 20)));
> >>>>>>>>>> #ifdef CONFIG_SMP
> >>>>>>>>>> raw_spin_lock_init(&cfs_rq->removed.lock);
> >>>>>>>>>> @@ -12378,6 +12469,7 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
> >>>>>>>>>> se->my_q = cfs_rq;
> >>>>>>>>>>
> >>>>>>>>>> se->latency_offset = calc_latency_offset(tg->latency_prio);
> >>>>>>>>>> + RB_CLEAR_NODE(&se->latency_node);
> >>>>>>>>>>
> >>>>>>>>>> /* guarantee group entities always have weight */
> >>>>>>>>>> update_load_set(&se->load, NICE_0_LOAD);
> >>>>>>>>>> @@ -12529,8 +12621,19 @@ int sched_group_set_latency(struct task_group *tg, int prio)
> >>>>>>>>>>
> >>>>>>>>>> for_each_possible_cpu(i) {
> >>>>>>>>>> struct sched_entity *se = tg->se[i];
> >>>>>>>>>> + struct rq *rq = cpu_rq(i);
> >>>>>>>>>> + struct rq_flags rf;
> >>>>>>>>>> + bool queued;
> >>>>>>>>>> +
> >>>>>>>>>> + rq_lock_irqsave(rq, &rf);
> >>>>>>>>>>
> >>>>>>>>>> + queued = __dequeue_latency(se->cfs_rq, se);
> >>>>>>>>>> WRITE_ONCE(se->latency_offset, latency_offset);
> >>>>>>>>>> + if (queued)
> >>>>>>>>>> + __enqueue_latency(se->cfs_rq, se, ENQUEUE_WAKEUP);
> >>>>>>>>>> +
> >>>>>>>>>> +
> >>>>>>>>>> + rq_unlock_irqrestore(rq, &rf);
> >>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> mutex_unlock(&shares_mutex);
> >>>>>>>>>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> >>>>>>>>>> index 9a2e71231083..21dd309e98a9 100644
> >>>>>>>>>> --- a/kernel/sched/sched.h
> >>>>>>>>>> +++ b/kernel/sched/sched.h
> >>>>>>>>>> @@ -570,6 +570,7 @@ struct cfs_rq {
> >>>>>>>>>> #endif
> >>>>>>>>>>
> >>>>>>>>>> struct rb_root_cached tasks_timeline;
> >>>>>>>>>> + struct rb_root_cached latency_timeline;
> >>>>>>>>>>
> >>>>>>>>>> /*
> >>>>>>>>>> * 'curr' points to currently running entity on this cfs_rq.
>
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