From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by sourceware.org (Postfix) with ESMTP id 3465838708A8 for ; Fri, 29 May 2020 13:13:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 3465838708A8 Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-108-OHPC4KQIM-O2EoruJOWDfw-1; Fri, 29 May 2020 09:13:06 -0400 X-MC-Unique: OHPC4KQIM-O2EoruJOWDfw-1 Received: by mail-qv1-f71.google.com with SMTP id s15so1075039qvo.6 for ; Fri, 29 May 2020 06:13:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=kJ9fu8SDO13L+GisOq6wUsyoOXWUJj22xQOYsW7iLVY=; b=iJSv8RQqn/Mz3vxGJbnd4tTPcbnD8m4JCP3iU8SR0x+XOdq5IVV/uBj4e5Na/oZbnw VP1vqsORec3rlX+2Zr3ZrIFoffnC5MGzLv1sgpBeZz8Pcm1n6hkCuz6MiveJExirrqGa IMDnbTPdaXGbDnukMkzwcJDMtcbTSm6sDkV8A7i5/EDViHG+Kn4JCXH/10lCkI0a3N3j IrzEy55cthhjGu9EMWxltcoVAqkrkls0JSUJUA1i1RHL2VddYJwpZP91tOwha273R3BZ 9bbEWiuIGVst7CcGd4OolsE+0TUtzS7setAsKpxFowbXYrg2YSe+8TpSGrUWvKU5GHhB SVcg== X-Gm-Message-State: AOAM531CR80FJEKWPK5mk7ZY61BM3SUKcdmFUqsB32Vj+4f3ZIyKiWVp uwFMgeZKz1a8/K1+S/vVrLeTS55nQ8rqI0g/KCpkEY7BA/pbwVO4N45tUa+wFqF6Uwwza0+Oipu aIRmflEkAvU+g5LqtKiCc X-Received: by 2002:a05:6214:b04:: with SMTP id u4mr1450369qvj.192.1590757985639; Fri, 29 May 2020 06:13:05 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw62lSbw1ug/RF3GdnQnrqZsr5m93oNdI1D35YoufVBEpUdtGLcYzET/sdkydeLcs+Dbgr2uA== X-Received: by 2002:a05:6214:b04:: with SMTP id u4mr1450342qvj.192.1590757985415; Fri, 29 May 2020 06:13:05 -0700 (PDT) Received: from [192.168.1.4] (198-84-170-103.cpe.teksavvy.com. [198.84.170.103]) by smtp.gmail.com with ESMTPSA id m126sm7135890qke.99.2020.05.29.06.13.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 May 2020 06:13:04 -0700 (PDT) Subject: Re: [PATCH] x86: Add thresholds for "rep movsb/stosb" to tunables To: "H.J. Lu" , liqingqing Cc: Hushiyuan , "libc-alpha@sourceware.org" References: <15ec783d-46f5-0166-aee9-f1d16a58ca83@huawei.com> From: Carlos O'Donell Organization: Red Hat Message-ID: Date: Fri, 29 May 2020 09:13:03 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 May 2020 13:13:11 -0000 On 5/23/20 12:37 AM, H.J. Lu via Libc-alpha wrote: > There is no single threshold value which is good for all workloads. > I don't think we should change REP_STOSB_THRESHOLD to 1MB. > On the other hand, the fixed threshold isn't flexible. Please try this > patch to see if you can set the threshold for your specific workload. My request here is that the manual include a documentation of what the minimums are for the tunable. Even an example reference of the minimum value would be useful for the tunable e.g. On AVX512 systems this value is X, on AVX systems this value is Y, on all other systems Z. -- Cheers, Carlos.