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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?+p+1CCT1x2c7RZbNz0N3lPBpBPkBkI5t0a1UFW7t3lrTLBvqpve7Va9yrNw+?= =?us-ascii?Q?r+xn+mfdUEDgZ+DX0jpOG5/ZBxAuBYQF968ibKi/YD6SOa+R/6F/L1L2YvvE?= =?us-ascii?Q?TruEE0Um62CqqpSxKRQb6fmbeG7IXWR8C9ZdqE8n/pWDhDdyu2xG3M874Wfz?= =?us-ascii?Q?xBAYniOWk6wgF03xPgyd7ypmlIziVTrz6X25/DF3Jd4oIC6TvhM8vB2Vkqy9?= =?us-ascii?Q?1h5V3BvmIWSqIpLtIzpc2KcPKsokP8pTwq2G19e+srXBywcgBjB1r1LDI0SF?= =?us-ascii?Q?Sant9ZQDfJaWomn8efTFppLDqgFd3Wt0EOXLxb0z//i7xsWq27zZSKj0O8gn?= =?us-ascii?Q?lEX9KHN7E804lqyHjIEB+yIExY9ql9ypYhK0bgcXOsUuathwNmFzi+uhK4Uc?= =?us-ascii?Q?NNOxc9ltMz5DVrM1p9qfP2AjL7IPJug1ZgsLY9XiELqu1V+BA5Rslf+BqMPQ?= =?us-ascii?Q?Ohrsb2f+ZD/qoWFFevCNuUfkywjC8xy5qFj5CNJKsD3xnhEQ8b/FbGNNkVs4?= =?us-ascii?Q?CCXoLD3+GKgGdPgcOt/0kxBFkcjGdB3MtU5bBVAAduMd22k4FxljLbn1aANN?= =?us-ascii?Q?Ir93NG8ADwHOawJzd4jF5XOFBGKCh30oaxAXTIq/f3xp5qf6kyeGWXHjH/Fc?= =?us-ascii?Q?V92cMS03hfCQ3d96Ymbz6O8FZOAYLltLPCOkumtC1s7PVVz2JTmEQD8qqCHi?= =?us-ascii?Q?aRoWMnlDX6XxZCa8cFqMuHSATu11cyLA4zFRXZZMGymv77cAts2VV617JtN1?= =?us-ascii?Q?4A6V/EVpVsbj5Y13Xu0j0z/qoKprhS/6dAiud7YYslnl8z59lIwKNtksf8p/?= =?us-ascii?Q?vBywC7WZHv/CNW/M8NhlyiTxl+oUlc3Tu+Clp2XWDXadTswnFbuCgeeX+/3N?= =?us-ascii?Q?Of1D7cr1ZbWFSrpWB+eYkDVuup4FSNwBDOm30Zp+SE5dJG4f6gKqcYOB/QGb?= =?us-ascii?Q?+P9bwXVVBwXGhvG811dCdK+3YJqoMDwIBzxHb0ScD31bmU/YpWlm1RDtuhqh?= =?us-ascii?Q?clGY9ybFhc8SIbK0YG2YnciAacGgEQ2A3kQOE6A87VHZhd1ov7TUSjbFUzdS?= =?us-ascii?Q?ZNWKuYKcH5I8CU9YOaiq6HjEgeoHVFjqdQzpqbaNpThP1KoLe5SWJ0gMzrhw?= =?us-ascii?Q?ZJ1Az3gkO7wW2aN9ZiZLlEl2ideeYTTSHxwITU1Csvdq/AtQoU2Tlmw/k2VW?= =?us-ascii?Q?muWsbdeq4QPLV+X5vMahw5aYV38lTIFh51sql/PJsqLd/Kz6y6O8jm59sdyg?= =?us-ascii?Q?FMi5PY8c0pFKOEXv3wCEite1UGHmq+xiu6/CIX7baad39vJ4kkJ8dmFbYCTa?= =?us-ascii?Q?RphSqOfy6pZp6kxin3AwC5KcFzXkxYy7K/XIamuCuNN12/YuShijQISFwEeN?= =?us-ascii?Q?24VjO+1AtFVO0+lcAwMurS9M0a+FiyB4kv050B24J8zvqFmGvCXhmHtAzAXF?= =?us-ascii?Q?IJ+IPlKO53/4HSstSSFKw5WrY1gaPvgBJcu2zZB2lg1bsCAcvoqmihHq8gkV?= =?us-ascii?Q?NVErTkw+JrX1DUVtyHXEgnL8BeI24IA0ST07hgGIwJQsDIwjVRPcXMrC4syN?= =?us-ascii?Q?VZJRJ6AaLBQqWELbcx0zNOEkaPs520utld8+/A3l?= X-MS-Exchange-CrossTenant-Network-Message-Id: 9fb9a779-d2e4-4b6a-1b5e-08da84deedd3 X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6206.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Aug 2022 08:10:23.6956 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: w10QcTs13Xlj4j6jxDCV/lpbzfNmxEitTsgD1WoyyoKAeMxKCCe0kXOMq3oRO5blG0JFYygLMe1cPmTQ00J1Zg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR11MB6019 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > >> > >> 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 > >> [https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net] > >> Tested-by: Yicong Yang > >> Signed-off-by: Barry Song > >> Signed-off-by: Yicong Yang > >> Reviewed-by: Tim Chen > >> --- > >> 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 > > > > 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)); > >> + } > >> + } > > . > >