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 ADCC6C433F5 for ; Tue, 17 May 2022 15:26:06 +0000 (UTC) Received: from localhost ([::1]:40998 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nqz5J-0001Dj-Hk for qemu-devel@archiver.kernel.org; Tue, 17 May 2022 11:26:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40338) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nqyzd-0001oK-UR for qemu-devel@nongnu.org; Tue, 17 May 2022 11:20:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:35263) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nqyzc-0008UU-BN for qemu-devel@nongnu.org; Tue, 17 May 2022 11:20:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652800811; 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=4faLPTe0FbYCrQ2LGEGOPPr/X7CA8tmjMoLl7F6IQ5E=; b=dIjF3hCv8H/lMu/qA30qkztFgGRM6JuV7Om7npz5U1CMI7stpqqNtt+0NekYr4Li7jK3R2 OxUL+p69djgAwpmQj4Gnz7/9aBZSWrDcD9zvE8pPLjHf1D4mAL9aZV6Nep3FNJrenYAiBm ZG+rPwbCDfR4ihxmTQ5Mlnats7kSABU= 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-47-86cFLM17Po-ezGMSgK069Q-1; Tue, 17 May 2022 11:20:07 -0400 X-MC-Unique: 86cFLM17Po-ezGMSgK069Q-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9FDF78032E5 for ; Tue, 17 May 2022 15:20:07 +0000 (UTC) Received: from localhost (unknown [10.39.194.27]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C10F40CF8F0; Tue, 17 May 2022 15:20:07 +0000 (UTC) Date: Tue, 17 May 2022 16:20:06 +0100 From: Stefan Hajnoczi To: Paolo Bonzini Cc: qemu-devel@nongnu.org, nsaenzju@redhat.com Subject: Re: [PATCH v3 1/3] thread-pool: optimize scheduling of completion bottom half Message-ID: References: <20220514065012.1149539-1-pbonzini@redhat.com> <20220514065012.1149539-2-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="WTTbQKmH4UDCBq2X" Content-Disposition: inline In-Reply-To: <20220514065012.1149539-2-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 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: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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" --WTTbQKmH4UDCBq2X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, May 14, 2022 at 08:50:10AM +0200, Paolo Bonzini wrote: > The completion bottom half was scheduled within the pool->lock > critical section. That actually results in worse performance, > because the worker thread can run its own small critical section > and go to sleep before the bottom half starts running. >=20 > Note that this simple change does not produce an improvement without > changing the thread pool QemuSemaphore to a condition variable. >=20 > Signed-off-by: Paolo Bonzini > Signed-off-by: Paolo Bonzini > --- > util/thread-pool.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) Reviewed-by: Stefan Hajnoczi --WTTbQKmH4UDCBq2X Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmKDvSUACgkQnKSrs4Gr c8jLYQf5AbfcsVX95Q196DMo1Aa9pa5KWn2KprqGJDeQBFQSYRhia2ltAmuHcMgm phdxeu1asc578Hit4/WJFSxfJJ4Quke1DVrAS1kgExfvgksnjan4oNFMoxqz/yzc oI/HCEyQ/1wN1m0dx+eMuFPqPtaR+hRXxjekBeeZfMW01mbL/0PcCMvLqpriKT/n qKmI0jY1EqlX0JVJ+8ehPRhbz8PoNKQ7v/Z/4+JAYWlU3Xs+6qv/4YJW7D7fBVV7 U2+UMGq9ypJvaD7bVFFdKF6zxePQSpbkB/F1KiHDnuMTejHC8DBtpNpIX3tIiHU3 LGZ6iPxlMhCnOd313eEAP2iMnv1N2g== =lc2C -----END PGP SIGNATURE----- --WTTbQKmH4UDCBq2X--