Messages in this thread Patch in this message | | | Date | Thu, 5 Oct 2023 11:26:07 +0530 | Subject | Re: [PATCH] sched/fair: Preserve PLACE_DEADLINE_INITIAL deadline | From | K Prateek Nayak <> |
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Hello Daniel,
On 10/4/2023 6:47 AM, Daniel Jordan wrote: > An entity is supposed to get an earlier deadline with > PLACE_DEADLINE_INITIAL when it's forked, but the deadline gets > overwritten soon after in enqueue_entity() the first time a forked > entity is woken so that PLACE_DEADLINE_INITIAL is effectively a no-op. > > Placing in task_fork_fair() seems unnecessary since none of the values > that get set (slice, vruntime, deadline) are used before they're set > again at enqueue time, so get rid of that and just pass ENQUEUE_INITIAL > to enqueue_entity() via wake_up_new_task(). > > Fixes: e8f331bcc270 ("sched/smp: Use lag to simplify cross-runqueue placement") > Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
I got a chance to this this on a 3rd Generation EPYC system. I don't see anything out of the ordinary except for a small regression on hackbench. I'll leave the full result below.
o System details
- 3rd Generation EPYC System - 2 sockets each with 64C/128T - NPS1 (Each socket is a NUMA node) - Boost enabled, C2 Disabled (POLL and MWAIT based C1 remained enabled)
o Kernel Details
- tip: tip:sched/core at commit d4d6596b4386 ("sched/headers: Remove duplicate header inclusions")
- place-deadline-fix: tip + this patch
o Benchmark Results
================================================================== Test : hackbench Units : Normalized time in seconds Interpretation: Lower is better Statistic : AMean ================================================================== Case: tip[pct imp](CV) place-deadline-fix[pct imp](CV) 1-groups 1.00 [ -0.00]( 2.58) 1.04 [ -3.63]( 3.14) 2-groups 1.00 [ -0.00]( 1.87) 1.03 [ -2.98]( 1.85) 4-groups 1.00 [ -0.00]( 1.63) 1.02 [ -2.35]( 1.59) 8-groups 1.00 [ -0.00]( 1.38) 1.03 [ -2.92]( 1.20) 16-groups 1.00 [ -0.00]( 2.67) 1.02 [ -1.61]( 2.08)
================================================================== Test : tbench Units : Normalized throughput Interpretation: Higher is better Statistic : AMean ================================================================== Clients: tip[pct imp](CV) place-deadline-fix[pct imp](CV) 1 1.00 [ 0.00]( 0.59) 1.02 [ 2.09]( 0.07) 2 1.00 [ 0.00]( 1.19) 1.02 [ 2.38]( 0.82) 4 1.00 [ 0.00]( 0.33) 1.03 [ 2.89]( 0.99) 8 1.00 [ 0.00]( 0.76) 1.02 [ 2.10]( 0.46) 16 1.00 [ 0.00]( 1.10) 1.01 [ 0.81]( 0.49) 32 1.00 [ 0.00]( 1.47) 1.02 [ 1.77]( 0.58) 64 1.00 [ 0.00]( 1.77) 1.02 [ 1.83]( 1.77) 128 1.00 [ 0.00]( 0.41) 1.02 [ 2.49]( 0.52) 256 1.00 [ 0.00]( 0.63) 1.03 [ 3.03]( 1.38) 512 1.00 [ 0.00]( 0.32) 1.02 [ 1.61]( 0.45) 1024 1.00 [ 0.00]( 0.22) 1.01 [ 1.00]( 0.26)
================================================================== Test : stream-10 Units : Normalized Bandwidth, MB/s Interpretation: Higher is better Statistic : HMean ================================================================== Test: tip[pct imp](CV) place-deadline-fix[pct imp](CV) Copy 1.00 [ 0.00]( 9.30) 0.85 [-15.36](11.26) Scale 1.00 [ 0.00]( 6.67) 0.98 [ -2.36]( 7.53) Add 1.00 [ 0.00]( 6.77) 0.92 [ -7.86]( 7.83) Triad 1.00 [ 0.00]( 7.36) 0.94 [ -5.57]( 6.82)
================================================================== Test : stream-100 Units : Normalized Bandwidth, MB/s Interpretation: Higher is better Statistic : HMean ================================================================== Test: tip[pct imp](CV) place-deadline-fix[pct imp](CV) Copy 1.00 [ 0.00]( 1.83) 0.96 [ -3.68]( 5.08) Scale 1.00 [ 0.00]( 6.41) 1.03 [ 2.66]( 5.28) Add 1.00 [ 0.00]( 6.23) 1.02 [ 1.54]( 4.97) Triad 1.00 [ 0.00]( 0.89) 0.94 [ -5.68]( 6.78)
================================================================== Test : netperf Units : Normalized Througput Interpretation: Higher is better Statistic : AMean ================================================================== Clients: tip[pct imp](CV) place-deadline-fix[pct imp](CV) 1-clients 1.00 [ 0.00]( 0.05) 1.02 [ 1.83]( 1.98) 2-clients 1.00 [ 0.00]( 0.93) 1.02 [ 1.87]( 2.45) 4-clients 1.00 [ 0.00]( 0.54) 1.02 [ 2.19]( 1.99) 8-clients 1.00 [ 0.00]( 0.48) 1.02 [ 2.29]( 2.27) 16-clients 1.00 [ 0.00]( 0.42) 1.02 [ 1.60]( 1.70) 32-clients 1.00 [ 0.00]( 0.78) 1.02 [ 1.88]( 2.08) 64-clients 1.00 [ 0.00]( 1.45) 1.02 [ 2.33]( 2.18) 128-clients 1.00 [ 0.00]( 0.97) 1.02 [ 2.38]( 1.95) 256-clients 1.00 [ 0.00]( 4.57) 1.02 [ 2.50]( 5.42) 512-clients 1.00 [ 0.00](52.74) 1.03 [ 3.38](49.69)
================================================================== Test : schbench Units : Normalized 99th percentile latency in us Interpretation: Lower is better Statistic : Median ================================================================== #workers: tip[pct imp](CV) place-deadline-fix[pct imp](CV) 1 1.00 [ -0.00]( 3.95) 0.90 [ 10.26](31.80) 2 1.00 [ -0.00](10.45) 1.08 [ -7.89](15.33) 4 1.00 [ -0.00]( 4.76) 0.93 [ 7.14]( 3.95) 8 1.00 [ -0.00]( 9.35) 1.06 [ -6.25]( 8.90) 16 1.00 [ -0.00]( 8.84) 0.92 [ 8.06]( 4.39) 32 1.00 [ -0.00]( 3.33) 1.04 [ -4.40]( 3.68) 64 1.00 [ -0.00]( 6.70) 0.96 [ 4.17]( 2.75) 128 1.00 [ -0.00]( 0.71) 0.96 [ 3.55]( 1.26) 256 1.00 [ -0.00](31.20) 1.28 [-28.21]( 9.69) 512 1.00 [ -0.00]( 4.98) 1.00 [ 0.48]( 2.76)
================================================================== Test : ycsb-cassandra Units : Normalized throughput Interpretation: Higher is better Statistic : Mean ================================================================== Metric tip place-deadline-fix(pct imp) Throughput 1.00 1.01 (%diff: 1.06%)
================================================================== Test : ycsb-mondodb Units : Normalized throughput Interpretation: Higher is better Statistic : Mean ================================================================== Metric tip place-deadline-fix(pct imp) Throughput 1.00 1.00 (%diff: 0.25%)
================================================================== Test : DeathStarBench Units : Normalized throughput Interpretation: Higher is better Statistic : Mean ================================================================== Pinning scaling tip place-deadline-fix(pct imp) 1CCD 1 1.00 1.00 (%diff: -0.32%) 2CCD 2 1.00 1.00 (%diff: -0.26%) 4CCD 4 1.00 1.00 (%diff: 0.17%) 8CCD 8 1.00 1.00 (%diff: -0.17%)
-- I see there is a v2. I'll give that a spin as well.
> --- > > Tested on top of peterz/sched/eevdf from 2023-10-03. > > kernel/sched/core.c | 2 +- > kernel/sched/fair.c | 1 - > 2 files changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 779cdc7969c81..500e2dbfd41dd 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4854,7 +4854,7 @@ void wake_up_new_task(struct task_struct *p) > update_rq_clock(rq); > post_init_entity_util_avg(p); > > - activate_task(rq, p, ENQUEUE_NOCLOCK); > + activate_task(rq, p, ENQUEUE_INITIAL | ENQUEUE_NOCLOCK); > trace_sched_wakeup_new(p); > wakeup_preempt(rq, p, WF_FORK); > #ifdef CONFIG_SMP > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index a0b4dac2662c9..5872b8a3f5891 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -12446,7 +12446,6 @@ static void task_fork_fair(struct task_struct *p) > curr = cfs_rq->curr; > if (curr) > update_curr(cfs_rq); > - place_entity(cfs_rq, se, ENQUEUE_INITIAL); > rq_unlock(rq, &rf); > } > -- Thanks and Regards, Prateek
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