From nobody Mon Feb 9 11:51:44 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1629107372750344.3138921154258; Mon, 16 Aug 2021 02:49:32 -0700 (PDT) Received: from localhost ([::1]:44402 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mFZFL-00011W-NN for importer@patchew.org; Mon, 16 Aug 2021 05:49:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58664) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mFZDy-00068t-Pc for qemu-devel@nongnu.org; Mon, 16 Aug 2021 05:48:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:35203) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mFZDx-0005Al-56 for qemu-devel@nongnu.org; Mon, 16 Aug 2021 05:48:06 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-521-vUMj8BYlPcqdm9yWXIGIAw-1; Mon, 16 Aug 2021 05:48:03 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1A17F9250C; Mon, 16 Aug 2021 09:48:02 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTP id BD52819C44; Mon, 16 Aug 2021 09:47:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629107284; 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: in-reply-to:in-reply-to:references:references; bh=RRfyEj5zq0PEQ0+kgM7gSJWllI0AQ1kkFp6Z0VAJNr0=; b=TKfAKtCFSo11m9qoRrIyC2BKRXQDVRo2yU8v07XD1omAXHHid+U0xLIZZsWl47hSyGCrCX LERarFbvcomotuw0H9CbnIyHpDphkkUsaQ5HL7ggdp93Cs0qDan9BXI9JlBIVyBY2IEnXe GdqE2EclIpreeFxqSbzUnrfMy2dQk0A= X-MC-Unique: vUMj8BYlPcqdm9yWXIGIAw-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v3 4/7] util/oslib-posix: Don't create too many threads with small memory or little pages Date: Mon, 16 Aug 2021 11:47:36 +0200 Message-Id: <20210816094739.21970-5-david@redhat.com> In-Reply-To: <20210816094739.21970-1-david@redhat.com> References: <20210816094739.21970-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Pankaj Gupta , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Eduardo Habkost , "Michael S. Tsirkin" , David Hildenbrand , "Dr . David Alan Gilbert" , Pankaj Gupta , Igor Mammedov , Paolo Bonzini Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1629107375882100001 Content-Type: text/plain; charset="utf-8" Let's limit the number of threads to something sane, especially that - We don't have more threads than the number of pages we have - We don't have threads that initialize small (< 64 MiB) memory Reviewed-by: Pankaj Gupta Reviewed-by: Dr. David Alan Gilbert Signed-off-by: David Hildenbrand Reviewed-by: Daniel P. Berrang=C3=A9 --- util/oslib-posix.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/util/oslib-posix.c b/util/oslib-posix.c index cf2ead54ad..67c08a425e 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -40,6 +40,7 @@ #include #include "qemu/cutils.h" #include "qemu/compiler.h" +#include "qemu/units.h" =20 #ifdef CONFIG_LINUX #include @@ -525,7 +526,8 @@ static void *do_madv_populate_write_pages(void *arg) return (void *)(uintptr_t)ret; } =20 -static inline int get_memset_num_threads(int smp_cpus) +static inline int get_memset_num_threads(size_t hpagesize, size_t numpages, + int smp_cpus) { long host_procs =3D sysconf(_SC_NPROCESSORS_ONLN); int ret =3D 1; @@ -533,6 +535,12 @@ static inline int get_memset_num_threads(int smp_cpus) if (host_procs > 0) { ret =3D MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cp= us); } + + /* Especially with gigantic pages, don't create more threads than page= s. */ + ret =3D MIN(ret, numpages); + /* Don't start threads to prealloc comparatively little memory. */ + ret =3D MIN(ret, MAX(1, hpagesize * numpages / (64 * MiB))); + /* In case sysconf() fails, we fall back to single threaded */ return ret; } @@ -542,7 +550,7 @@ static int touch_all_pages(char *area, size_t hpagesize= , size_t numpages, { static gsize initialized =3D 0; MemsetContext context =3D { - .num_threads =3D get_memset_num_threads(smp_cpus), + .num_threads =3D get_memset_num_threads(hpagesize, numpages, smp_c= pus), }; size_t numpages_per_thread, leftover; void *(*touch_fn)(void *); --=20 2.31.1