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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 6E767C32750 for ; Fri, 2 Aug 2019 08:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 415262187F for ; Fri, 2 Aug 2019 08:30:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="P60KY2Io" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404216AbfHBIaX (ORCPT ); Fri, 2 Aug 2019 04:30:23 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:44064 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404200AbfHBIaX (ORCPT ); Fri, 2 Aug 2019 04:30:23 -0400 Received: by mail-wr1-f67.google.com with SMTP id p17so76247261wrf.11; Fri, 02 Aug 2019 01:30:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:references:user-agent:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=mfmWYxXmISm2SzEPyTKOCPMMxxIYkBzLdw5KHd5IvKs=; b=P60KY2IoLhMeA0gUqbbe9lbAwoI+hx21aQf12e+sIm/+hrfQNH82NaL35EZx1SOcsJ sLRVsy1sFMS++fF/tjERdnDFy1/JuW+tXccHREfdLgFulsz9OI4lPfCzJpz86mDisEqJ DBx2dFlh5aVeorRHZnKe1BeVQJfTy1vQ3AlFX87gYm83sR4En49DlPWyM+BKcTOeAYtI EpoXrQHxH6yj4pzY7O5j3B8okR8/3dxdEYCiQQpO2h89QEsKfKq3Ydh5pD9gr0LqKnQp 1RYpqz3IrNV5IvJrGSPARjgewB6NUE3O9ATiFwqeSR2N/q3DtSBohbRbXb0HRyc+6P9p hDqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:references:user-agent:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=mfmWYxXmISm2SzEPyTKOCPMMxxIYkBzLdw5KHd5IvKs=; b=nGwH7mfEIb7kMrdVGMrX1ukiIMmb+/xz7iD+ucHej6fadWrnRJznfRqK6zXTY7bprf DNyhcg1G/BhLVDAJqCQu+mtnabQdXcO76DeSLOUvdA/7funmYZWBh9M9qpggBZPSTupa F91A0mtcWqYiUVobZCJ8dhQCO8gVEdnWHnG7HI8EhUqmNBfJYra0xvw5zjoL2nd7wwjn xVLwKt1Ke5TC8rA2224G4rSTtqf8RnhIgNzLCuIu/HHwEIoh4v3aptBqPD7Qc5BPTat0 /8OoES0jtcu7V2YUJo/9dfN/AeOl4WNGpNJgRIYFY0vnd8fH2L/mHL0VlmEtoHaw0mZt QDYg== X-Gm-Message-State: APjAAAUf+1KWmqIUUkbr0tXD1fKwLUfg3lj+v87XfzFbEOnqvWzxr2C5 WMskdwsjc8rIXyjFasfuKwk= X-Google-Smtp-Source: APXvYqwL5rjpBjAEAaBUBmoJ9tvEgwf3fBPbdtTM1oOqr46Jgpp71NhD/XYVJhRLzxJrZaIueeKe2Q== X-Received: by 2002:adf:8bc2:: with SMTP id w2mr62660881wra.7.1564734620724; Fri, 02 Aug 2019 01:30:20 -0700 (PDT) Received: from crazypad.dinechin.lan ([2a01:e35:8b6a:1220:f3dc:ccbc:638a:c410]) by smtp.gmail.com with ESMTPSA id f10sm62284117wrs.22.2019.08.02.01.30.19 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 02 Aug 2019 01:30:19 -0700 (PDT) From: Christophe de Dinechin X-Google-Original-From: Christophe de Dinechin References: <1564479235-25074-1-git-send-email-wanpengli@tencent.com> <04700afaf68114b5ab329f5a5182e21578c15795.camel@suse.com> User-agent: mu4e 1.3.2; emacs 26.2 To: Dario Faggioli Cc: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH] KVM: Disable wake-affine vCPU process to mitigate lock holder preemption In-reply-to: <04700afaf68114b5ab329f5a5182e21578c15795.camel@suse.com> Date: Fri, 02 Aug 2019 10:30:11 +0200 Message-ID: <7h7e7wkm0c.fsf@crazypad.dinechin.lan> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dario Faggioli writes: > On Tue, 2019-07-30 at 17:33 +0800, Wanpeng Li wrote: >> However, in multiple VMs over-subscribe virtualization scenario, it >> increases >> the probability to incur vCPU stacking which means that the sibling >> vCPUs from >> the same VM will be stacked on one pCPU. I test three 80 vCPUs VMs >> running on >> one 80 pCPUs Skylake server(PLE is supported), the ebizzy score can >> increase 17% >> after disabling wake-affine for vCPU process. >> > Can't we achieve this by removing SD_WAKE_AFFINE from the relevant > scheduling domains? By acting on > /proc/sys/kernel/sched_domain/cpuX/domainY/flags, I mean? > > Of course this will impact all tasks, not only KVM vcpus. But if the > host does KVM only anyway... Even a host dedicated to KVM has many non-KVM processes. I suspect an increasing number of hosts will be split between VMs and containers. > > Regards -- Cheers, Christophe de Dinechin