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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 E1FCCC46477 for ; Thu, 13 Jun 2019 22:55:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB5B721537 for ; Thu, 13 Jun 2019 22:55:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726796AbfFMWzK (ORCPT ); Thu, 13 Jun 2019 18:55:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41120 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfFMWzK (ORCPT ); Thu, 13 Jun 2019 18:55:10 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 417B785363; Thu, 13 Jun 2019 22:55:10 +0000 (UTC) Received: from amt.cnet (ovpn-112-4.gru2.redhat.com [10.97.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C5526085B; Thu, 13 Jun 2019 22:55:06 +0000 (UTC) Received: from amt.cnet (localhost [127.0.0.1]) by amt.cnet (Postfix) with ESMTP id 16506105181; Thu, 13 Jun 2019 19:53:03 -0300 (BRT) Received: (from marcelo@localhost) by amt.cnet (8.14.7/8.14.7/Submit) id x5DMqwSl025647; Thu, 13 Jun 2019 19:52:58 -0300 Message-ID: <20190613224532.949768676@redhat.com> User-Agent: quilt/0.66 Date: Thu, 13 Jun 2019 18:45:32 -0400 From: Marcelo Tosatti To: kvm-devel Cc: Paolo Bonzini , Radim Krcmar , Andrea Arcangeli , "Rafael J. Wysocki" , Peter Zijlstra , Wanpeng Li , Konrad Rzeszutek Wilk , Raslan KarimAllah , Boris Ostrovsky , Ankur Arora , Christian Borntraeger , linux-pm@vger.kernel.org Subject: [patch 0/5] cpuidle haltpoll driver and governor (v4) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 13 Jun 2019 22:55:10 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The cpuidle-haltpoll driver with haltpoll governor allows the guest vcpus to poll for a specified amount of time before halting. This provides the following benefits to host side polling: 1) The POLL flag is set while polling is performed, which allows a remote vCPU to avoid sending an IPI (and the associated cost of handling the IPI) when performing a wakeup. 2) The VM-exit cost can be avoided. The downside of guest side polling is that polling is performed even with other runnable tasks in the host. Results comparing halt_poll_ns and server/client application where a small packet is ping-ponged: host --> 31.33 halt_poll_ns=300000 / no guest busy spin --> 33.40 (93.8%) halt_poll_ns=0 / guest_halt_poll_ns=300000 --> 32.73 (95.7%) For the SAP HANA benchmarks (where idle_spin is a parameter of the previous version of the patch, results should be the same): hpns == halt_poll_ns idle_spin=0/ idle_spin=800/ idle_spin=0/ hpns=200000 hpns=0 hpns=800000 DeleteC06T03 (100 thread) 1.76 1.71 (-3%) 1.78 (+1%) InsertC16T02 (100 thread) 2.14 2.07 (-3%) 2.18 (+1.8%) DeleteC00T01 (1 thread) 1.34 1.28 (-4.5%) 1.29 (-3.7%) UpdateC00T03 (1 thread) 4.72 4.18 (-12%) 4.53 (-5%) V2: - Move from x86 to generic code (Paolo/Christian) - Add auto-tuning logic (Paolo) - Add MSR to disable host side polling (Paolo) V3: - Do not be specific about HLT VM-exit in the documentation (Ankur Arora) - Mark tuning parameters static and __read_mostly (Andrea Arcangeli) - Add WARN_ON if host does not support poll control (Joao Martins) - Use sched_clock and cleanup haltpoll_enter_idle (Peter Zijlstra) - Mark certain functions in kvm.c as static (kernel test robot) - Remove tracepoints as they use RCU from extended quiescent state (kernel test robot) V4: - Use a haltpoll governor, use poll_state.c poll code (Rafael J. Wysocki)