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 7687DC46467 for ; Wed, 11 Jan 2023 12:11:15 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pFZwc-0001Gt-AA; Wed, 11 Jan 2023 07:11:02 -0500 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 1pFZwa-0001EV-Jz for qemu-devel@nongnu.org; Wed, 11 Jan 2023 07:11:00 -0500 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 1pFZwY-0005yJ-RT for qemu-devel@nongnu.org; Wed, 11 Jan 2023 07:11:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673439057; h=from:from:reply-to: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=3IEeE2SI/VvR5TjHhjpxE9Uifws8p8zg+4BJ9WEjtp4=; b=FQ3yIFM2r5m/AjKlPMFUatzdjd1b+Yk11AOJaSX3sAntMZGbeAkSm552TkHxXT8d3ZGJdb ozp+MqajtW1eQF0LssOnaOtDvnhVJFTx6IghK+lm6rlZaO2IWnmgQI85aBX4hUtyLtNygu W8Jj1+M84VY8kLZ78uZ8SzePDeR9ucY= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-643-dxicMeLLMgWUFYDPncPQ7g-1; Wed, 11 Jan 2023 07:10:56 -0500 X-MC-Unique: dxicMeLLMgWUFYDPncPQ7g-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 5649C3C0F223; Wed, 11 Jan 2023 12:10:56 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.119]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A0F4C40C2064; Wed, 11 Jan 2023 12:10:55 +0000 (UTC) Date: Wed, 11 Jan 2023 12:10:53 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Emilio Cota Cc: qemu-devel@nongnu.org, Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH 2/2] tcg: use QTree instead of GTree Message-ID: References: <20230111035536.309885-1-cota@braap.org> <20230111035536.309885-3-cota@braap.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230111035536.309885-3-cota@braap.org> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Jan 10, 2023 at 10:55:36PM -0500, Emilio Cota wrote: > qemu-user can hang in a multi-threaded fork. One common > reason is that when creating a TB, between fork and exec > we manipulate a GTree whose memory allocator (GSlice) is > not fork-safe. > > Although POSIX does not mandate it, the system's allocator > (e.g. tcmalloc, libc malloc) is probably fork-safe. > > Fix some of these hangs by using QTree, which uses > the system's allocator. > > For more details, see: > https://gitlab.com/qemu-project/qemu/-/issues/285 > > Performance impact on linux-user: > - ~2% slowdown in spec06 > - 1.05% slowdown in Nbench-int > - 4.51% slowdown in Nbench-fp What do you get *before* applying this patch, if you just run linux-user with G_SLICE=always-malloc set ? Also what libc impl were you testing with ? glibc or musl or something else ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|