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 53C51C54E58 for ; Wed, 20 Mar 2024 14:10:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rmwdU-0005iY-Vu; Wed, 20 Mar 2024 10:09:45 -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 1rmwdT-0005hr-Sb for qemu-devel@nongnu.org; Wed, 20 Mar 2024 10:09:43 -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 1rmwdR-0004AQ-Ug for qemu-devel@nongnu.org; Wed, 20 Mar 2024 10:09:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710943780; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wWC3NPJ5B4V/3836lJ+D7CEtSyOJnNma4teub39CUpQ=; b=TTRVhb5nfID+vfFYrDxd9EGdxLVOOdcKRHvQQeNpKm50noq5IS/ceIt8e4msKHs6QIQQeS a6SStApPorKZel+CZsuHuc0LipB0Z+VEvVI2POdt9FDsSA7delM6lbJfVXb/ntQ4/aL2P9 5AziJBCncr958YNrnuiqqzGIIEqQZW8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-153-yHUTaCpGNYyu5AUjSfGgDg-1; Wed, 20 Mar 2024 10:09:39 -0400 X-MC-Unique: yHUTaCpGNYyu5AUjSfGgDg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2B301181B7AE for ; Wed, 20 Mar 2024 14:09:39 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.205]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 482E42022C1D; Wed, 20 Mar 2024 14:09:37 +0000 (UTC) Date: Wed, 20 Mar 2024 14:09:32 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Kevin Wolf , Sanjay Rao , Boaz Ben Shabat , Joe Mario Subject: Re: [PATCH] coroutine: cap per-thread local pool size Message-ID: References: <20240318183429.1039340-1-stefanha@redhat.com> <20240319175510.GA1127203@fedora> <20240320133539.GA1190824@fedora> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240320133539.GA1190824@fedora> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 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: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.417, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: , 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 Wed, Mar 20, 2024 at 09:35:39AM -0400, Stefan Hajnoczi wrote: > On Tue, Mar 19, 2024 at 08:10:49PM +0000, Daniel P. Berrangé wrote: > > On Tue, Mar 19, 2024 at 01:55:10PM -0400, Stefan Hajnoczi wrote: > > > On Tue, Mar 19, 2024 at 01:43:32PM +0000, Daniel P. Berrangé wrote: > > > > On Mon, Mar 18, 2024 at 02:34:29PM -0400, Stefan Hajnoczi wrote: > > > > > diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c > > > > > index 5fd2dbaf8b..2790959eaf 100644 > > > > > --- a/util/qemu-coroutine.c > > > > > +++ b/util/qemu-coroutine.c > > > > > > > > > +static unsigned int get_global_pool_hard_max_size(void) > > > > > +{ > > > > > +#ifdef __linux__ > > > > > + g_autofree char *contents = NULL; > > > > > + int max_map_count; > > > > > + > > > > > + /* > > > > > + * Linux processes can have up to max_map_count virtual memory areas > > > > > + * (VMAs). mmap(2), mprotect(2), etc fail with ENOMEM beyond this limit. We > > > > > + * must limit the coroutine pool to a safe size to avoid running out of > > > > > + * VMAs. > > > > > + */ > > > > > + if (g_file_get_contents("/proc/sys/vm/max_map_count", &contents, NULL, > > > > > + NULL) && > > > > > + qemu_strtoi(contents, NULL, 10, &max_map_count) == 0) { > > > > > + /* > > > > > + * This is a conservative upper bound that avoids exceeding > > > > > + * max_map_count. Leave half for non-coroutine users like library > > > > > + * dependencies, vhost-user, etc. Each coroutine takes up 2 VMAs so > > > > > + * halve the amount again. > > > > Leaving half for loaded libraries, etc is quite conservative > > if max_map_count is the small-ish 64k default. > > > > That reservation could perhaps a fixed number like 5,000 ? > > While I don't want QEMU to abort, once this heuristic is in the code it > will be scary to make it more optimistic and we may never change it. So > now is the best time to try 5,000. > > I'll send a follow-up patch that reserves 5,000 mappings. If that turns > out to be too optimistic we can increase the reservation. BTW, I suggested 5,000, because I looked at a few QEM processes I have running on Fedora and saw just under 1,000 lines in /proc/$PID/maps, of which only a subset is library mappings. So multiplying that x5 felt like a fairly generous overhead for more complex build configurations. 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 :|