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[23.128.96.32]) by mx.google.com with ESMTPS id h2-20020a170902f54200b001c5c370d4d3si2069545plf.534.2023.10.20.07.34.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Oct 2023 07:34:38 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) client-ip=23.128.96.32; Authentication-Results: mx.google.com; dkim=pass header.i=@gmx.de header.s=s31663417 header.b=hpPXWP9T; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gmx.de Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by agentk.vger.email (Postfix) with ESMTP id B1D0982999E1; Fri, 20 Oct 2023 07:34:36 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at agentk.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377527AbjJTOea (ORCPT + 99 others); Fri, 20 Oct 2023 10:34:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377490AbjJTOe3 (ORCPT ); Fri, 20 Oct 2023 10:34:29 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8670219E for ; Fri, 20 Oct 2023 07:34:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1697812460; x=1698417260; i=efault@gmx.de; bh=QtJgWLvcgIWB43JrJ3u31jdplw3iBoNu/v4f26qo2fA=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To: References; b=hpPXWP9T8mJAG6PJ8JeF406xbDL5oBtRmynvMhXqsl65rVZf2HeJ8gnff0Bfp+J4 xj7PBJudw+7ip+edSiubEnig4n6uZ1Wq6XwvVGCWNQvt5+eXyUhUEXyXupuo97kZx 2qPpcrTtnk/ARPJ2Xi8KgGyoy0PdSBl+kubaPREkCrX9l+OszyFkwwWdr1T3v+whn 4+UyB3gGB5XpLZfIoQO9hpCgQs+U4w1UnSlbC7IpHfXaOG4Cth2AxWPik2d7qbMQK QLQVl+XrVJWc1Nuvw1oRDCHoic4athO3FztH8YuzKi4NUpqkaJhbY5wVUbawtfRUJ ksv7mlfOrmNPYwj+kg== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from homer.fritz.box ([185.221.149.246]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1M8ygO-1qq0Z02qxC-0066nj; Fri, 20 Oct 2023 16:34:20 +0200 Message-ID: <15e4768144a74b093ad5a43f6e5c263fd98775fb.camel@gmx.de> Subject: Re: Runtime overhead of PREEMPT_DYNAMIC From: Mike Galbraith To: Emanuele Rocca Cc: linux-kernel@vger.kernel.org, Michal Hocko Date: Fri, 20 Oct 2023 16:34:20 +0200 In-Reply-To: References: <7a818250a8f36476f13b57a172fdb1ab23645edc.camel@gmx.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:8oyPL33s02edddKEsSveNr9iAosXPTOe/lzFTOVkDghMEJpBGNe dyCbS4IOHOWWMOHUWrcJG3OSkQoNh+w3+SBOCaJpeqOyFVzSTs5e8+mGadXDGoFFzTlOx8M 0avAXVkB+5v6/Oty7M8BBQKVkO+uR4hKiDlwtclah2P5yBeBniYm1yLEXS9mDqOIxin9Ft0 6Dst8iLYnjBnnzeoiNZxg== UI-OutboundReport: notjunk:1;M01:P0:9R5zOUn2Nuo=;jq/QxVtimCoPk1ThZ8ObCzfVcLM iPexu0Om9A2Qnm3LBQebH4pcJb4GVyiXE5eRJc+33m0oTR79zoIKQZ3zffeCREOmXPJzIkr2N /gBnsk7H1voHZ0F2x1NnNcLV3Ni1xgRZT5MqDmRWVW2bm8WXibGKFBjBY76Ri0eX2En2oqnde 4UEj96oonJN8e8k1Npj7uO8A4cP57blROEbnLcxAWseLFiyUfy353B95MqP7vjQMj+AKIHWx+ w+S/TwjcCpEIddgHxYDeo5llcfRcEEG11pS6MIFvn2IhA87syWcaaVoj3rF82l3ez0CzwyVUd 7lczBV57oR67tf7lXO4unFgq+m9h+TQG9KkkhOLgF+v49+GuBUKeAgZiuhg3A/UVpelPKHC+j ubbeSkOUAByopWG19accylqqt32/SGh+5HuYWzFdUWnF4DfMTmnL9nofiULLLuwjtOgnfgpz1 KDa3FCWCl+VMDlsQx6CMd21UcmNOcOW/PdQiwzX88oPbjS2sirciBWcxGsf/dAs+7Ir0F5ybg LQBBmlWZRXiQOKFeq6UzVJOabxoDahyEl+m/sSec7sFoshWHEZUw/Xrvt6cM7TSkaIt+AEaxH ELM9hj+tmBrQNVFn/A3M56BiZbN4qAfltXo6lB99WJ6ACGXNntZsKY091N+6xK3i/np+43ZbJ QCAF5QMRrIyFWErcagADnTEl5GI1SHQzQ0LK2b8sOy/hSxK9K+t6hD0QUpmKOK+zC25NHer99 fXRosbkSBh+Mv86dHELIZ+0w4zQT45l/gV4F4Qd74ymmFunnDSDX8qPiXnpCsCTM0FtFo3C6b 4ml8WjwYk9bOhBWQMJ9AJDjxa5xdZXZ2HxOdCSNPRj7kgHbAFlHKSni8H8glCon3mTuqAO32r T2BwWj+oGmNuHUarplE82eNu+4Rukmizz97tejlchKUZljInZUVnGNzJ1guSuOrPCPMq3N4Lf pcMxhNI6lbwJOGlCbIrXDmFnEAQ= X-Spam-Status: No, score=-0.6 required=5.0 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=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Fri, 20 Oct 2023 07:34:36 -0700 (PDT) On Fri, 2023-10-20 at 16:11 +0200, Mike Galbraith wrote: > On Fri, 2023-10-20 at 15:40 +0200, Emanuele Rocca wrote: > > Hi Mike, > > > > Here is the full diff between the kernel configurations I used. The on= ly > > change I made was setting CONFIG_PREEMPT_DYNAMIC=3Dn, everything else = was > > a consequence of that AFAICT, but please do let me know if you see > > anything that shouldn't be there. > > > > --- config-6.5.0-0.preempt-dynamic-amd64=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A02023-10-11 15:30:02.000000000 +0200 > > +++ config-6.5.0-0.a.test-amd64=C2=A02023-10-11 14:30:02.000000000 +02= 00 > > > > @@ -10597,7 +10596,6 @@ > > =C2=A0# end of Scheduler Debugging > > =C2=A0 > > =C2=A0# CONFIG_DEBUG_TIMEKEEPING is not set > > -CONFIG_DEBUG_PREEMPT=3Dy > > =C2=A0 > > =C2=A0# > > =C2=A0# Lock Debugging (spinlocks, mutexes, etc...) > > Seems you had also turned on DEBUG_PREEMPT in the dynamic setup, which > adds some overhead.. but not a metric ton. Hm, I don't recall the overhead as being that bad, but thar she blows. i7-4790 avg cmdline 6.5.8-voluntary 3685.08 3679.93 3704.98 3689.99 1.000 6.5.8-dynamic 3571.62 3568.61 3550.55 3563.59 .965 3052.06 3032.74 3019.93 3034.91 .822 +DEBUG_PREEMPT 3651.37 3599.87 3615.18 3622.14 .981 preempt=3Dnone 3459.58 3514.09 3539.88 3504.51 .949 preempt=3Dfull