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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7001FC2D0CE for ; Tue, 21 Jan 2020 15:46:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 41F3822314 for ; Tue, 21 Jan 2020 15:46:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="n2THz0sT"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OzeW8bYu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41F3822314 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gPbK/UkhcyvB/PQDfEqZoDZR56rjznfSumWZZ09IwMk=; b=n2THz0sTXZfVCK Kew67Tz9d6udhSpRnBCIjXSkMjPpjwgLvsq7VNKMNTzHQVtymYRgbzezW8TdvPL/25uVQ2SN9kaak c5ANljknWEifafzrtPJYhpF919KhuEsJCLQOpg4bfEe1edzRJHeAoeQn9ICjU//kw/tJ3890lXiPk 5ZZ22GHftqglGAYek1DYs7a51yGFe9EcULfnFyEs5vNyO6AniK9HZcX7b1m++h8CUw5UbEVjuprIg dEvy3ib+ag9kiiLvXScaYtG9RFNVLTMaEyXnaEcX3xGekgQ+Z7h7kb2bjEN4MpwwoipPBC8iOdP1o GiFlND1IZbqJwmXjSeXQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1itvjE-0004p1-96; Tue, 21 Jan 2020 15:46:08 +0000 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120] helo=us-smtp-1.mimecast.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1itvj7-0004oC-Gt for linux-arm-kernel@lists.infradead.org; Tue, 21 Jan 2020 15:46:07 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579621558; 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=X4V9D6y2Lif4i/Bl6mgnfeFczMOxy2sAL0UfSmHDkVo=; b=OzeW8bYuAKEgom0xLx2Di74U+k1L95/BkI3zk37R8HXXAI6idL0uJOvxySUe0auygoTNK7 YZ5/NGm0t879LGF5tfakM3umgrm1nt9MI95SxHiQUjZEVqIV7uEq2bb5uM396hqHLYiNHJ ijqFCKnZFkCYnKyNjNtoD/T6TPmU1IE= 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-367-6I1zfnugNnqKXYuU_fxsGg-1; Tue, 21 Jan 2020 10:45:54 -0500 X-MC-Unique: 6I1zfnugNnqKXYuU_fxsGg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 774E68045C0; Tue, 21 Jan 2020 15:45:51 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-59.bos.redhat.com [10.18.17.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C488860F8; Tue, 21 Jan 2020 15:45:49 +0000 (UTC) Subject: Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA To: Peter Zijlstra , Alex Kogan References: <20191230194042.67789-1-alex.kogan@oracle.com> <20191230194042.67789-5-alex.kogan@oracle.com> <20200121132949.GL14914@hirez.programming.kicks-ass.net> From: Waiman Long Organization: Red Hat Message-ID: Date: Tue, 21 Jan 2020 10:45:48 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20200121132949.GL14914@hirez.programming.kicks-ass.net> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200121_074601_638692_367C63E6 X-CRM114-Status: GOOD ( 14.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, guohanjun@huawei.com, arnd@arndb.de, dave.dice@oracle.com, jglauber@marvell.com, x86@kernel.org, will.deacon@arm.com, linux@armlinux.org.uk, linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, steven.sistare@oracle.com, tglx@linutronix.de, daniel.m.jordan@oracle.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/21/20 8:29 AM, Peter Zijlstra wrote: > On Mon, Dec 30, 2019 at 02:40:41PM -0500, Alex Kogan wrote: > >> +/* >> + * Controls the threshold for the number of intra-node lock hand-offs before >> + * the NUMA-aware variant of spinlock is forced to be passed to a thread on >> + * another NUMA node. By default, the chosen value provides reasonable >> + * long-term fairness without sacrificing performance compared to a lock >> + * that does not have any fairness guarantees. The default setting can >> + * be changed with the "numa_spinlock_threshold" boot option. >> + */ >> +int intra_node_handoff_threshold __ro_after_init = 1 << 16; > There is a distinct lack of quantitative data to back up that > 'reasonable' claim there. > > Where is the table of inter-node latencies observed for the various > values tested, and on what criteria is this number deemed reasonable? > > To me, 64k lock hold times seems like a giant number, entirely outside > of reasonable. I actually had similar question before, but having the capability of changing the default with boot time parameter alleviate some of my concern. I will certainly like to see actual data on how different values will affect the performance of the code. Cheers, Longman _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel