From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 048F7C43460 for ; Fri, 23 Apr 2021 12:48:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB3CE61404 for ; Fri, 23 Apr 2021 12:48:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242528AbhDWMtY (ORCPT ); Fri, 23 Apr 2021 08:49:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230413AbhDWMtV (ORCPT ); Fri, 23 Apr 2021 08:49:21 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE17CC061756 for ; Fri, 23 Apr 2021 05:48:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=d+62syAUKVHnyCs4R/YinMObJcTHmOL48njuvbToqKc=; b=PNSVmEfj7RyCKZh7Y3aZCJE4f0 p9goePTU8TUPrpIQw6H9YWzoyY22zAPPVxvoack2lFNzLLdXF4wgzlrx8xXh1rbBOXt2vzfZNf04T ntmvGddFCQbtBqtq+nBk7C+MQV+RBhZN4YHgao7TjbzAAvbreQgJSyA3YbinZmECk3KWRLTOIjQwd 2D45w7LkgKFdoYfMDHxQXyj4DpeFUHixO/N+/HDdnpGt6Ngze0lPriX+ZKQ9UOUSBLTu6wltpOw+6 GdZJU5OWMN2S691nkL2waPvUfk15tXmp7asEc9lIwFW7wldC8qIgUt8U7LzaWKmPGCwlrxb4pDLV/ GxpXvJwQ==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lZvDt-001r9N-1h; Fri, 23 Apr 2021 12:48:11 +0000 Date: Fri, 23 Apr 2021 13:47:53 +0100 From: Matthew Wilcox To: lkp Cc: David Howells , Christoph Hellwig , LKML , lkp@lists.01.org, lkp@intel.com, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@intel.com Subject: Re: [mm/writeback] e5dbd33218: will-it-scale.per_process_ops -3.8% regression Message-ID: <20210423124753.GA235567@casper.infradead.org> References: <20210423054601.GC13944@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210423054601.GC13944@xsang-OptiPlex-9020> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 23, 2021 at 01:46:01PM +0800, kernel test robot wrote: > FYI, we noticed a -3.8% regression of will-it-scale.per_process_ops due to commit: > commit: e5dbd33218bd8d87ab69f730ab90aed5fab7eb26 ("mm/writeback: Add wait_on_page_writeback_killable") That commit just adds a function. It doesn't add any callers. It must just be moving something around ... > 39f985c8f667c80a e5dbd33218bd8d87ab69f730ab9 > ---------------- --------------------------- > %stddev %change %stddev > \ | \ > 9359770 -3.8% 9001769 will-it-scale.16.processes > 584985 -3.8% 562610 will-it-scale.per_process_ops > 9359770 -3.8% 9001769 will-it-scale.workload > 15996 -1.2% 15811 proc-vmstat.nr_kernel_stack > 23577 ± 10% +18.5% 27937 ± 7% softirqs.CPU48.SCHED > 5183 ± 41% +47.2% 7630 ± 7% interrupts.CPU1.NMI:Non-maskable_interrupts > 5183 ± 41% +47.2% 7630 ± 7% interrupts.CPU1.PMI:Performance_monitoring_interrupts > 54.33 ± 12% +18.4% 64.33 ± 7% perf-sched.wait_and_delay.count.schedule_hrtimeout_range_clock.poll_schedule_timeout.constprop.0.do_sys_poll > 153.34 ± 24% -45.9% 83.00 ± 25% perf-sched.wait_and_delay.max.ms.schedule_timeout.rcu_gp_kthread.kthread.ret_from_fork > 153.33 ± 24% -45.9% 82.99 ± 25% perf-sched.wait_time.max.ms.schedule_timeout.rcu_gp_kthread.kthread.ret_from_fork > 2.424e+10 -3.8% 2.332e+10 perf-stat.i.branch-instructions > 0.47 +3.7% 0.48 perf-stat.i.cpi > 2.529e+10 -4.0% 2.428e+10 perf-stat.i.dTLB-loads > 1.15e+10 -3.8% 1.106e+10 perf-stat.i.dTLB-stores > 54249733 -4.8% 51627939 perf-stat.i.iTLB-load-misses > 1.004e+11 -3.8% 9.661e+10 perf-stat.i.instructions > 2.15 -3.6% 2.07 perf-stat.i.ipc > 693.66 -3.9% 666.70 perf-stat.i.metric.M/sec > 0.46 +3.7% 0.48 perf-stat.overall.cpi > 2.15 -3.6% 2.08 perf-stat.overall.ipc > 2.416e+10 -3.8% 2.324e+10 perf-stat.ps.branch-instructions > 2.52e+10 -4.0% 2.419e+10 perf-stat.ps.dTLB-loads > 1.146e+10 -3.8% 1.102e+10 perf-stat.ps.dTLB-stores > 54065825 -4.8% 51454019 perf-stat.ps.iTLB-load-misses > 1.001e+11 -3.8% 9.628e+10 perf-stat.ps.instructions > 3.025e+13 -3.9% 2.908e+13 perf-stat.total.instructions > 0.89 ± 14% -0.1 0.77 ± 11% perf-profile.calltrace.cycles-pp.atime_needs_update.touch_atime.shmem_mmap.mmap_region.do_mmap > 0.14 ± 13% -0.1 0.04 ± 71% perf-profile.children.cycles-pp.common_mmap > 0.61 ± 12% -0.1 0.52 ± 12% perf-profile.children.cycles-pp.common_file_perm > 0.21 ± 8% -0.0 0.17 ± 11% perf-profile.children.cycles-pp.vma_set_page_prot > 0.12 ± 8% -0.0 0.09 ± 12% perf-profile.children.cycles-pp.blocking_notifier_call_chain > 0.12 ± 14% -0.0 0.09 ± 15% perf-profile.children.cycles-pp.get_mmap_base > 0.09 ± 8% -0.0 0.07 ± 11% perf-profile.children.cycles-pp.vm_pgprot_modify > 0.13 ± 15% +0.1 0.19 ± 8% perf-profile.children.cycles-pp.cap_capable > 0.03 ±102% +0.1 0.12 ± 12% perf-profile.children.cycles-pp.munmap@plt > 0.14 ± 13% +0.1 0.24 ± 6% perf-profile.children.cycles-pp.testcase > 0.33 ± 10% -0.1 0.23 ± 10% perf-profile.self.cycles-pp.cap_vm_enough_memory > 0.13 ± 11% -0.1 0.03 ±100% perf-profile.self.cycles-pp.common_mmap > 0.48 ± 12% -0.1 0.41 ± 12% perf-profile.self.cycles-pp.common_file_perm > 0.49 ± 12% -0.1 0.43 ± 13% perf-profile.self.cycles-pp.vm_area_alloc > 0.12 ± 8% -0.0 0.09 ± 12% perf-profile.self.cycles-pp.blocking_notifier_call_chain > 0.12 ± 13% -0.0 0.09 ± 14% perf-profile.self.cycles-pp.get_mmap_base > 0.11 ± 8% +0.0 0.16 ± 10% perf-profile.self.cycles-pp.__x64_sys_munmap > 0.11 ± 14% +0.1 0.18 ± 8% perf-profile.self.cycles-pp.cap_capable > 0.12 ± 11% +0.1 0.20 ± 6% perf-profile.self.cycles-pp.testcase > 0.01 ±223% +0.1 0.11 ± 13% perf-profile.self.cycles-pp.munmap@plt I'm struggling to see anything in that that says anything other than "we did 3-4% less work". Maybe someone else has something useful to say about it?