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 4A864C54E58 for ; Thu, 21 Mar 2024 10:44:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rnFti-0007ja-Ln; Thu, 21 Mar 2024 06:43:46 -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 1rnFth-0007jP-7l for qemu-devel@nongnu.org; Thu, 21 Mar 2024 06:43:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rnFtf-0005uT-A5 for qemu-devel@nongnu.org; Thu, 21 Mar 2024 06:43:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1711017820; 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=Prjpfmy1k2jOOV/EkJQ+Pwos+LtxEYWH5eWuds2LtGs=; b=R+6Vpb9nUDqbdmGkApZymBtvBQwY3dA/HdztBcMriDNvQeWQOoawkX4ktrRMCu4QP7tARv ZGnzySBkVD0tlpiHU4oWRAlz6yTAtrK/xaP6dtaIP1K+So+S2h9Pgag2IhB1uAUjpVQRrf sowE2/+Dlq3pIPVBW1bHoDhbjbkWgqI= 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-210-P5HRrab9MaiBu3jdY-EUZg-1; Thu, 21 Mar 2024 06:43:38 -0400 X-MC-Unique: P5HRrab9MaiBu3jdY-EUZg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (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 C1664800262 for ; Thu, 21 Mar 2024 10:43:37 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.56]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1A7921C060CE; Thu, 21 Mar 2024 10:43:36 +0000 (UTC) Date: Thu, 21 Mar 2024 10:43:30 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Kevin Wolf Subject: Re: [PATCH] coroutine: reserve 5,000 mappings Message-ID: References: <20240320181232.1464819-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240320181232.1464819-1-stefanha@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; 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=-0.372, 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 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 02:12:32PM -0400, Stefan Hajnoczi wrote: > Daniel P. Berrangé pointed out that the coroutine > pool size heuristic is very conservative. Instead of halving > max_map_count, he suggested reserving 5,000 mappings for non-coroutine > users based on observations of guests he has access to. > > Fixes: 86a637e48104 ("coroutine: cap per-thread local pool size") It wasn't really broken, so "Tweaks" or "Enhances" rather than "Fixes" if you like :-) > Signed-off-by: Stefan Hajnoczi > --- > util/qemu-coroutine.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c > index 2790959eaf..eb4eebefdf 100644 > --- a/util/qemu-coroutine.c > +++ b/util/qemu-coroutine.c > @@ -377,12 +377,17 @@ static unsigned int get_global_pool_hard_max_size(void) > 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. > + * This is an upper bound that avoids exceeding max_map_count. Leave a > + * fixed amount for non-coroutine users like library dependencies, > + * vhost-user, etc. Each coroutine takes up 2 VMAs so halve the > + * remaining amount. > */ > - return max_map_count / 4; > + if (max_map_count > 5000) { > + return (max_map_count - 5000) / 2; > + } else { > + /* Disable the global pool but threads still have local pools */ > + return 0; > + } > } > #endif Reviewed-by: Daniel P. Berrangé 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 :|