From patchwork Wed Mar 20 18:12:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13598076 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 E3BDEC6FD1F for ; Wed, 20 Mar 2024 18:13:51 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rn0Qy-00055K-3g; Wed, 20 Mar 2024 14:13:04 -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 1rn0Qv-000541-CF for qemu-devel@nongnu.org; Wed, 20 Mar 2024 14:13:01 -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 1rn0Qt-0000ql-O9 for qemu-devel@nongnu.org; Wed, 20 Mar 2024 14:13:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710958378; 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: content-transfer-encoding:content-transfer-encoding; bh=mx6Q2LgUKDHVhhD+C8LfRUbyuNAf3z39vNdeSsc5VEk=; b=Ater1UnzL2LVGSrpMAfyMRdoGgGafaOSo4GPcc6fW/sIHtQLo8ipo6/cnYYJ4/0oJkqmaO zHcQHE7YNXe4HwoPLc5urpH8J3HKaRtHfnnG6G5If+30pLPXY41j68rkKVXDT3VuWISmOx 04qTd2b90flA83g9ky/1W6APEJELgp8= 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-111-g_UMKql_PReK6iaPoQxuGA-1; Wed, 20 Mar 2024 14:12:56 -0400 X-MC-Unique: g_UMKql_PReK6iaPoQxuGA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (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 01E1F101A586 for ; Wed, 20 Mar 2024 18:12:55 +0000 (UTC) Received: from localhost (unknown [10.39.192.79]) by smtp.corp.redhat.com (Postfix) with ESMTP id 17826111E406; Wed, 20 Mar 2024 18:12:54 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi Subject: [PATCH] coroutine: reserve 5,000 mappings Date: Wed, 20 Mar 2024 14:12:32 -0400 Message-ID: <20240320181232.1464819-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 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: -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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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") Signed-off-by: Stefan Hajnoczi Reviewed-by: Daniel P. Berrangé --- 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