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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 75729C77B7A for ; Thu, 1 Jun 2023 13:18:58 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q4iC0-0006iU-S9; Thu, 01 Jun 2023 09:18:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q4iBt-0006hf-TI for qemu-devel@nongnu.org; Thu, 01 Jun 2023 09:18:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q4iBr-0002pf-IO for qemu-devel@nongnu.org; Thu, 01 Jun 2023 09:18:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685625486; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=s1oHRD2FrvYDtBzunw8ehneh7jdPHUY38x6ImHPiTfs=; b=SBRZ6ON60JF1EMBGCQW/X1C3/HJ1Dnj7qXIzpwl5FXbxtKd8npBsaR/R2ECExfidFZO5ww J1WcI/Be++ul2sdud0L64WZ94p52dzSnBKnolvo8rdQ+ZGFszca21zvnGbSZSZXuBbnTuS wpR+96N3iRzR6dp1YXteBqpnn15KYK8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-543-3mDHGk81PguLD52fVfEqQQ-1; Thu, 01 Jun 2023 09:17:59 -0400 X-MC-Unique: 3mDHGk81PguLD52fVfEqQQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 30072862F5E; Thu, 1 Jun 2023 13:17:39 +0000 (UTC) Received: from localhost (unknown [10.39.194.5]) by smtp.corp.redhat.com (Postfix) with ESMTP id AEF68111F3B0; Thu, 1 Jun 2023 13:17:38 +0000 (UTC) Date: Thu, 1 Jun 2023 09:17:37 -0400 From: Stefan Hajnoczi To: =?utf-8?B?THVrw6HFoQ==?= Doktor Cc: Stefan Hajnoczi , qemu-devel Subject: Re: Performance improvement and regression with 6d740fb01b9f0f5ea7a82f4d5e458d91940a19ee Message-ID: <20230601131737.GD1538357@fedora> References: <34c16474-2022-455a-a506-58a8d2b6c3a6@redhat.com> <3584ed8c-e60c-54bd-1abe-8294e985119a@redhat.com> <36fd7ce5-38d2-59db-d182-3ded498319ee@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Qh/wfGWfio0BDnIx" Content-Disposition: inline In-Reply-To: <36fd7ce5-38d2-59db-d182-3ded498319ee@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.166, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --Qh/wfGWfio0BDnIx Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jun 01, 2023 at 06:23:21AM +0200, Luk=C3=A1=C5=A1 Doktor wrote: > Dne 31. 05. 23 v 19:14 Stefan Hajnoczi napsal(a): > > On Wed, 31 May 2023 at 12:50, Luk=C3=A1=C5=A1 Doktor wrote: > >> > >> Dne 26. 05. 23 v 12:56 Stefan Hajnoczi napsal(a): > >>> On Fri, 26 May 2023 at 04:07, Luk=C3=A1=C5=A1 Doktor wrote: > >>>> > >>>> Dne 25. 05. 23 v 17:21 Stefan Hajnoczi napsal(a): > >>>>> On Thu, 25 May 2023 at 06:18, Luk=C3=A1=C5=A1 Doktor wrote: > >>>>>> the perf-ci detected and bisected the 6d740fb - aio-posix: do not = nest poll handlers - as a performance improvement when using multiple concu= rrent jobs and 4k (22%) as well as 1024k (63%) blocks on aarch64 (on a slow= rotational disk). > >>>>>> > >>>>>> https://ldoktor.github.io/tmp/RedHat-virtlab-arm09/v8.0.0/150-= improvement.html > >>>>>> > >>>>>> Based on the commit message I guess it's expected so take this jus= t as a record of an improvement. > >>>>> > >>>>> The commit was not intended to change performance and I'm not sure = why > >>>>> it happens! > >>>>> > >>>> > >>>> It had and today the x86_64 pipeline finished which shows similar im= provement just not in read but rather in write instead and only for 4k bloc= ks (~40%). For 1024k blocks I can see it scoring a bit better (~1.5%). Read= s are too jittery to really tell anything on that machine. Anyway I have no= t done any thorough testing, just a bisection with the most significant set= ting. > >>>> > >>>> From around the same time I can see a NVMe regression in 4k writes, = but first bisection job showed nothing. I'll increase the range and try aga= in as each job since that day shows similar drop. > >>> > >> > >> Hello Stefan, folks, > >> > >> the regression proved to be there and stably reproducible. With NVMe 4= k writes with jobs=3D10 and iodepth=3D4 I can see a 50% regression on my ma= chine: > >> > >> https://ldoktor.github.io/tmp/RedHat-virtlab722/v8.0.0/150-regress= ion.html > >> > >> The rest of the cases doesn't show any change at all. I can provide mo= re data if someone is interested. > >=20 > > Which commit caused the regression? >=20 > Hello Stefan, >=20 > the same one that caused the improvement on rotational disks: 6d740fb01b9= f0f5ea7a82f4d5e458d91940a19ee Thanks. This commit definitely needs more investigation. I didn't expect it to have a noticeable effect. I will take a look in July. Stefan --Qh/wfGWfio0BDnIx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmR4mnEACgkQnKSrs4Gr c8hmqQf+MpC48qQJrrm1sL5kO9EB33p14qrDIYpq+aQ3ihwHrHJ8hEU8x2j+DQU9 WGvAceBgpdOx2px6GDO+At0K1sKtMzECVh3bfT1VrBDjcKEIKfddfLF24CaSQT5V thOXz+aA+tatbGXp40caydqN44PC4z2r/hx1Ykhl/uPbkzjAY2g76dPj0Ix/qsO7 WOrTowLYPV507aO2PY4lJQPeUVNTU92m9rtMYEgQr+BCVNCfRCXBKYXlO+R1Xr5J asQcTSXH6k8bD4JbXYktesIJi86ZRDt2e67Q1LhtTty+tGJNmYdI2+IWhqd8vMcp GX46UZ7Wx1xpv/Z7tKb/dQ83x2yq3A== =lmba -----END PGP SIGNATURE----- --Qh/wfGWfio0BDnIx--