| Message ID | 20220822073610.27205-3-yangyicong@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | sched/fair: Scan cluster before scanning LLC in wake-up path | expand |
On 2022-08-22 at 15:36:10 +0800, Yicong Yang wrote: > From: Barry Song <song.bao.hua@hisilicon.com> > > For platforms having clusters like Kunpeng920, CPUs within the same cluster > have lower latency when synchronizing and accessing shared resources like > cache. Thus, this patch tries to find an idle cpu within the cluster of the > target CPU before scanning the whole LLC to gain lower latency. > > Testing has been done on Kunpeng920 by pinning tasks to one numa and two > numa. On Kunpeng920, Each numa has 8 clusters and each cluster has 4 CPUs. > > With this patch, We noticed enhancement on tbench within one numa or cross > two numa. > > On numa 0: > 6.0-rc1 patched > Hmean 1 351.20 ( 0.00%) 396.45 * 12.88%* > Hmean 2 700.43 ( 0.00%) 793.76 * 13.32%* > Hmean 4 1404.42 ( 0.00%) 1583.62 * 12.76%* > Hmean 8 2833.31 ( 0.00%) 3147.85 * 11.10%* > Hmean 16 5501.90 ( 0.00%) 6089.89 * 10.69%* > Hmean 32 10428.59 ( 0.00%) 10619.63 * 1.83%* > Hmean 64 8223.39 ( 0.00%) 8306.93 * 1.02%* > Hmean 128 7042.88 ( 0.00%) 7068.03 * 0.36%* > > On numa 0-1: > 6.0-rc1 patched > Hmean 1 363.06 ( 0.00%) 397.13 * 9.38%* > Hmean 2 721.68 ( 0.00%) 789.84 * 9.44%* > Hmean 4 1435.15 ( 0.00%) 1566.01 * 9.12%* > Hmean 8 2776.17 ( 0.00%) 3007.05 * 8.32%* > Hmean 16 5471.71 ( 0.00%) 6103.91 * 11.55%* > Hmean 32 10164.98 ( 0.00%) 11531.81 * 13.45%* > Hmean 64 17143.28 ( 0.00%) 20078.68 * 17.12%* > Hmean 128 14552.70 ( 0.00%) 15156.41 * 4.15%* > Hmean 256 12827.37 ( 0.00%) 13326.86 * 3.89%* > > Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so the SMT branch > in the code has not been tested but it supposed to work. > > Suggested-by: Peter Zijlstra <peterz@infradead.org> > [https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net] > Tested-by: Yicong Yang <yangyicong@hisilicon.com> > Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> > Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> > Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> > --- > kernel/sched/fair.c | 30 +++++++++++++++++++++++++++--- > kernel/sched/sched.h | 2 ++ > kernel/sched/topology.c | 10 ++++++++++ > 3 files changed, 39 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 914096c5b1ae..6fa77610d0f5 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6437,6 +6437,30 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > } > } > > + if (static_branch_unlikely(&sched_cluster_active)) { > + struct sched_domain *sdc = rcu_dereference(per_cpu(sd_cluster, target)); > + > + if (sdc) { > + for_each_cpu_wrap(cpu, sched_domain_span(sdc), target + 1) { Looks good to me. One minor question, why don't we use cpumask_and(cpus, sched_domain_span(sdc), cpus); > + if (!cpumask_test_cpu(cpu, cpus)) > + continue; so above check can be removed in each loop? Besides may I know what version this patch is based on? since I failed to apply the patch on v6.0-rc2. Other than that: Reviewed-by: Chen Yu <yu.c.chen@intel.com> thanks, Chenyu > + > + if (has_idle_core) { > + i = select_idle_core(p, cpu, cpus, &idle_cpu); > + if ((unsigned int)i < nr_cpumask_bits) > + return i; > + } else { > + if (--nr <= 0) > + return -1; > + idle_cpu = __select_idle_cpu(cpu, p); > + if ((unsigned int)idle_cpu < nr_cpumask_bits) > + return idle_cpu; > + } > + } > + cpumask_andnot(cpus, cpus, sched_domain_span(sdc)); > + } > + }
On 2022/8/23 11:45, Chen Yu wrote: > On 2022-08-22 at 15:36:10 +0800, Yicong Yang wrote: >> From: Barry Song <song.bao.hua@hisilicon.com> >> >> For platforms having clusters like Kunpeng920, CPUs within the same cluster >> have lower latency when synchronizing and accessing shared resources like >> cache. Thus, this patch tries to find an idle cpu within the cluster of the >> target CPU before scanning the whole LLC to gain lower latency. >> >> Testing has been done on Kunpeng920 by pinning tasks to one numa and two >> numa. On Kunpeng920, Each numa has 8 clusters and each cluster has 4 CPUs. >> >> With this patch, We noticed enhancement on tbench within one numa or cross >> two numa. >> >> On numa 0: >> 6.0-rc1 patched >> Hmean 1 351.20 ( 0.00%) 396.45 * 12.88%* >> Hmean 2 700.43 ( 0.00%) 793.76 * 13.32%* >> Hmean 4 1404.42 ( 0.00%) 1583.62 * 12.76%* >> Hmean 8 2833.31 ( 0.00%) 3147.85 * 11.10%* >> Hmean 16 5501.90 ( 0.00%) 6089.89 * 10.69%* >> Hmean 32 10428.59 ( 0.00%) 10619.63 * 1.83%* >> Hmean 64 8223.39 ( 0.00%) 8306.93 * 1.02%* >> Hmean 128 7042.88 ( 0.00%) 7068.03 * 0.36%* >> >> On numa 0-1: >> 6.0-rc1 patched >> Hmean 1 363.06 ( 0.00%) 397.13 * 9.38%* >> Hmean 2 721.68 ( 0.00%) 789.84 * 9.44%* >> Hmean 4 1435.15 ( 0.00%) 1566.01 * 9.12%* >> Hmean 8 2776.17 ( 0.00%) 3007.05 * 8.32%* >> Hmean 16 5471.71 ( 0.00%) 6103.91 * 11.55%* >> Hmean 32 10164.98 ( 0.00%) 11531.81 * 13.45%* >> Hmean 64 17143.28 ( 0.00%) 20078.68 * 17.12%* >> Hmean 128 14552.70 ( 0.00%) 15156.41 * 4.15%* >> Hmean 256 12827.37 ( 0.00%) 13326.86 * 3.89%* >> >> Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so the SMT branch >> in the code has not been tested but it supposed to work. >> >> Suggested-by: Peter Zijlstra <peterz@infradead.org> >> [https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net] >> Tested-by: Yicong Yang <yangyicong@hisilicon.com> >> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> >> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> >> Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> >> --- >> kernel/sched/fair.c | 30 +++++++++++++++++++++++++++--- >> kernel/sched/sched.h | 2 ++ >> kernel/sched/topology.c | 10 ++++++++++ >> 3 files changed, 39 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 914096c5b1ae..6fa77610d0f5 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -6437,6 +6437,30 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool >> } >> } >> >> + if (static_branch_unlikely(&sched_cluster_active)) { >> + struct sched_domain *sdc = rcu_dereference(per_cpu(sd_cluster, target)); >> + >> + if (sdc) { >> + for_each_cpu_wrap(cpu, sched_domain_span(sdc), target + 1) { > Looks good to me. One minor question, why don't we use > cpumask_and(cpus, sched_domain_span(sdc), cpus); >> + if (!cpumask_test_cpu(cpu, cpus)) >> + continue; > so above check can be removed in each loop? Since we'll need to recalculate the mask of rest CPUs to test in the LLC after scanning the cluster CPUs. > Besides may I know what version this patch > is based on? since I failed to apply the patch on v6.0-rc2. Other than that: > It's on 6.0-rc1 when sent but can be cleanly rebased on rc2: yangyicong@ubuntu:~/mainline_linux/linux_sub_workspace$ git log --oneline -3 0079c27ba265 (HEAD -> topost-cls-v7, topost-cls-v6) sched/fair: Scan cluster before scanning LLC in wake-up path 1ecb9e322bd7 sched: Add per_cpu cluster domain info and cpus_share_lowest_cache API 1c23f9e627a7 (tag: v6.0-rc2, origin/master, origin/HEAD, master) Linux 6.0-rc2 So I'm not sure where's the problem... > Reviewed-by: Chen Yu <yu.c.chen@intel.com> > Thanks! > thanks, > Chenyu >> + >> + if (has_idle_core) { >> + i = select_idle_core(p, cpu, cpus, &idle_cpu); >> + if ((unsigned int)i < nr_cpumask_bits) >> + return i; >> + } else { >> + if (--nr <= 0) >> + return -1; >> + idle_cpu = __select_idle_cpu(cpu, p); >> + if ((unsigned int)idle_cpu < nr_cpumask_bits) >> + return idle_cpu; >> + } >> + } >> + cpumask_andnot(cpus, cpus, sched_domain_span(sdc)); >> + } >> + } > . >
On 2022-08-23 at 15:48:00 +0800, Yicong Yang wrote: > On 2022/8/23 11:45, Chen Yu wrote: > > On 2022-08-22 at 15:36:10 +0800, Yicong Yang wrote: > >> From: Barry Song <song.bao.hua@hisilicon.com> > >> > >> For platforms having clusters like Kunpeng920, CPUs within the same cluster > >> have lower latency when synchronizing and accessing shared resources like > >> cache. Thus, this patch tries to find an idle cpu within the cluster of the > >> target CPU before scanning the whole LLC to gain lower latency. > >> > >> Testing has been done on Kunpeng920 by pinning tasks to one numa and two > >> numa. On Kunpeng920, Each numa has 8 clusters and each cluster has 4 CPUs. > >> > >> With this patch, We noticed enhancement on tbench within one numa or cross > >> two numa. > >> > >> On numa 0: > >> 6.0-rc1 patched > >> Hmean 1 351.20 ( 0.00%) 396.45 * 12.88%* > >> Hmean 2 700.43 ( 0.00%) 793.76 * 13.32%* > >> Hmean 4 1404.42 ( 0.00%) 1583.62 * 12.76%* > >> Hmean 8 2833.31 ( 0.00%) 3147.85 * 11.10%* > >> Hmean 16 5501.90 ( 0.00%) 6089.89 * 10.69%* > >> Hmean 32 10428.59 ( 0.00%) 10619.63 * 1.83%* > >> Hmean 64 8223.39 ( 0.00%) 8306.93 * 1.02%* > >> Hmean 128 7042.88 ( 0.00%) 7068.03 * 0.36%* > >> > >> On numa 0-1: > >> 6.0-rc1 patched > >> Hmean 1 363.06 ( 0.00%) 397.13 * 9.38%* > >> Hmean 2 721.68 ( 0.00%) 789.84 * 9.44%* > >> Hmean 4 1435.15 ( 0.00%) 1566.01 * 9.12%* > >> Hmean 8 2776.17 ( 0.00%) 3007.05 * 8.32%* > >> Hmean 16 5471.71 ( 0.00%) 6103.91 * 11.55%* > >> Hmean 32 10164.98 ( 0.00%) 11531.81 * 13.45%* > >> Hmean 64 17143.28 ( 0.00%) 20078.68 * 17.12%* > >> Hmean 128 14552.70 ( 0.00%) 15156.41 * 4.15%* > >> Hmean 256 12827.37 ( 0.00%) 13326.86 * 3.89%* > >> > >> Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so the SMT branch > >> in the code has not been tested but it supposed to work. > >> > >> Suggested-by: Peter Zijlstra <peterz@infradead.org> > >> [https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net] > >> Tested-by: Yicong Yang <yangyicong@hisilicon.com> > >> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> > >> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> > >> Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> > >> --- > >> kernel/sched/fair.c | 30 +++++++++++++++++++++++++++--- > >> kernel/sched/sched.h | 2 ++ > >> kernel/sched/topology.c | 10 ++++++++++ > >> 3 files changed, 39 insertions(+), 3 deletions(-) > >> > >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > >> index 914096c5b1ae..6fa77610d0f5 100644 > >> --- a/kernel/sched/fair.c > >> +++ b/kernel/sched/fair.c > >> @@ -6437,6 +6437,30 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > >> } > >> } > >> > >> + if (static_branch_unlikely(&sched_cluster_active)) { > >> + struct sched_domain *sdc = rcu_dereference(per_cpu(sd_cluster, target)); > >> + > >> + if (sdc) { > >> + for_each_cpu_wrap(cpu, sched_domain_span(sdc), target + 1) { > > Looks good to me. One minor question, why don't we use > > cpumask_and(cpus, sched_domain_span(sdc), cpus); > >> + if (!cpumask_test_cpu(cpu, cpus)) > >> + continue; > > so above check can be removed in each loop? > > Since we'll need to recalculate the mask of rest CPUs to test in the LLC after scanning the cluster CPUs. > I was thinking of introducing a temporary variable cpumask_and(cpus_cluster, sched_domain_span(sdc), cpus); and iterate this cpus_cluster in the loop. But since the cpus is reused, it is ok to be as it is. > > Besides may I know what version this patch > > is based on? since I failed to apply the patch on v6.0-rc2. Other than that: > > > > It's on 6.0-rc1 when sent but can be cleanly rebased on rc2: > > yangyicong@ubuntu:~/mainline_linux/linux_sub_workspace$ git log --oneline -3 > 0079c27ba265 (HEAD -> topost-cls-v7, topost-cls-v6) sched/fair: Scan cluster before scanning LLC in wake-up path > 1ecb9e322bd7 sched: Add per_cpu cluster domain info and cpus_share_lowest_cache API I did not apply 1/2, and that was why it failed I think. Thanks for explaination. Thanks, Chenyu > 1c23f9e627a7 (tag: v6.0-rc2, origin/master, origin/HEAD, master) Linux 6.0-rc2 > > So I'm not sure where's the problem... > > > Reviewed-by: Chen Yu <yu.c.chen@intel.com> > > > > Thanks! > > > thanks, > > Chenyu > >> + > >> + if (has_idle_core) { > >> + i = select_idle_core(p, cpu, cpus, &idle_cpu); > >> + if ((unsigned int)i < nr_cpumask_bits) > >> + return i; > >> + } else { > >> + if (--nr <= 0) > >> + return -1; > >> + idle_cpu = __select_idle_cpu(cpu, p); > >> + if ((unsigned int)idle_cpu < nr_cpumask_bits) > >> + return idle_cpu; > >> + } > >> + } > >> + cpumask_andnot(cpus, cpus, sched_domain_span(sdc)); > >> + } > >> + } > > . > >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 914096c5b1ae..6fa77610d0f5 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6437,6 +6437,30 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool } } + if (static_branch_unlikely(&sched_cluster_active)) { + struct sched_domain *sdc = rcu_dereference(per_cpu(sd_cluster, target)); + + if (sdc) { + for_each_cpu_wrap(cpu, sched_domain_span(sdc), target + 1) { + if (!cpumask_test_cpu(cpu, cpus)) + continue; + + if (has_idle_core) { + i = select_idle_core(p, cpu, cpus, &idle_cpu); + if ((unsigned int)i < nr_cpumask_bits) + return i; + } else { + if (--nr <= 0) + return -1; + idle_cpu = __select_idle_cpu(cpu, p); + if ((unsigned int)idle_cpu < nr_cpumask_bits) + return idle_cpu; + } + } + cpumask_andnot(cpus, cpus, sched_domain_span(sdc)); + } + } + for_each_cpu_wrap(cpu, cpus, target + 1) { if (has_idle_core) { i = select_idle_core(p, cpu, cpus, &idle_cpu); @@ -6444,7 +6468,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool return i; } else { - if (!--nr) + if (--nr <= 0) return -1; idle_cpu = __select_idle_cpu(cpu, p); if ((unsigned int)idle_cpu < nr_cpumask_bits) @@ -6543,7 +6567,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) /* * If the previous CPU is cache affine and idle, don't be stupid: */ - if (prev != target && cpus_share_cache(prev, target) && + if (prev != target && cpus_share_lowest_cache(prev, target) && (available_idle_cpu(prev) || sched_idle_cpu(prev)) && asym_fits_capacity(task_util, prev)) return prev; @@ -6569,7 +6593,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) p->recent_used_cpu = prev; if (recent_used_cpu != prev && recent_used_cpu != target && - cpus_share_cache(recent_used_cpu, target) && + cpus_share_lowest_cache(recent_used_cpu, target) && (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) && cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && asym_fits_capacity(task_util, recent_used_cpu)) { diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index e9f0935605e2..60e8a91e29d1 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1815,7 +1815,9 @@ DECLARE_PER_CPU(struct sched_domain __rcu *, sd_cluster); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_numa); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); + extern struct static_key_false sched_asym_cpucapacity; +extern struct static_key_false sched_cluster_active; struct sched_group_capacity { atomic_t ref; diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8ab27c0d6d1f..04ead3227201 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -670,7 +670,9 @@ DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa); DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); + DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity); +DEFINE_STATIC_KEY_FALSE(sched_cluster_active); static void update_top_cache_domain(int cpu) { @@ -2268,6 +2270,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att struct rq *rq = NULL; int i, ret = -ENOMEM; bool has_asym = false; + bool has_cluster = false; if (WARN_ON(cpumask_empty(cpu_map))) goto error; @@ -2289,6 +2292,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att sd = build_sched_domain(tl, cpu_map, attr, sd, i); has_asym |= sd->flags & SD_ASYM_CPUCAPACITY; + has_cluster |= sd->flags & SD_CLUSTER; if (tl == sched_domain_topology) *per_cpu_ptr(d.sd, i) = sd; @@ -2399,6 +2403,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att if (has_asym) static_branch_inc_cpuslocked(&sched_asym_cpucapacity); + if (has_cluster) + static_branch_inc_cpuslocked(&sched_cluster_active); + if (rq && sched_debug_verbose) { pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); @@ -2498,6 +2505,9 @@ static void detach_destroy_domains(const struct cpumask *cpu_map) if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu))) static_branch_dec_cpuslocked(&sched_asym_cpucapacity); + if (rcu_access_pointer(per_cpu(sd_cluster, cpu))) + static_branch_dec_cpuslocked(&sched_cluster_active); + rcu_read_lock(); for_each_cpu(i, cpu_map) cpu_attach_domain(NULL, &def_root_domain, i);