sched/fair: Scan cluster before scanning LLC in wake-up path
kunpeng inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5W44S CVE: NA Reference: https://lore.kernel.org/lkml/20220915073423.25535-1-yangyicong@huawei.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> Reviewed-by:
Chen Yu <yu.c.chen@intel.com> Signed-off-by:
Jie Liu <liujie375@h-partners.com>
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