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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2ECF7C43217 for ; Fri, 11 Nov 2022 10:18:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233469AbiKKKSJ (ORCPT ); Fri, 11 Nov 2022 05:18:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233519AbiKKKRO (ORCPT ); Fri, 11 Nov 2022 05:17:14 -0500 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9005871F22 for ; Fri, 11 Nov 2022 02:17:12 -0800 (PST) Received: by mail-wr1-x433.google.com with SMTP id k8so5876817wrh.1 for ; Fri, 11 Nov 2022 02:17:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:user-agent:message-id:in-reply-to:date:references :subject:cc:to:from:from:to:cc:subject:date:message-id:reply-to; bh=BH/APi1a0PoKAJZknP8AkAonpu9TnXBBnNUq+HUkcwM=; b=4oOscMH7jU6ury8coe6FqLy7zK1XZNinWBvFR7izLUhT8UO+Uf7A34vnnALOX+0uZw 6u0BzpFG7Xf65rlpJuAvjMgTNhVx/gSKcxgRlSDN2zH7W+6LI6BnNcuT8FnlleBan74e U+nnWKJgynFDrs5h1v4LHjxM1v+N8pvPWTcuhFJiAYBmZcFqEaaRiyqBxAjt+VLKVj27 ymKqo1xHrZ7qEJ3SsTyk8ixNapD9K4j74hbbeGy2nwxMGfxLNJInz1YB3DFYiKEqav4a oeGBzhxJPbF4jd3XpyzDJKvMeI1dC4S63nsd7WzmmwS7/SrtVuS1+i59tvEjxRd8GW0+ CSgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:user-agent:message-id:in-reply-to:date:references :subject:cc:to:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=BH/APi1a0PoKAJZknP8AkAonpu9TnXBBnNUq+HUkcwM=; b=UlSOcROASLxtRa8UmzrN+JrctEjPn0aEJ6TaiBWROaD3eMuateOqCtN6QtqeGP4F+h qmXbey1+d/Ih02CpNZWcHDYCjFqJxS2k1az+RLJSxpEp/Fsz1UJBdRZ9gJVW2bLgX9sf fMLDEEjc270lTDeBQZGhnLw762M0r6EqkhqsjXpS5lj4/V95ZPdXetpjwSQSWki8ikC7 VctKPV5NDpcsx5vn9ncPQV62xXqAOTG9/XCCIV1E8XYiK7plqWKfyr+CqM7SPmiyfKhk Aq+JYd4FJpAV3Tlk8XDq1i8HV2y3ymBCjiw/gQauR19iLZpfNYzB7yVvtuL/hXbhBDW2 wSTw== X-Gm-Message-State: ANoB5plo8L1b03mpEC8RYKC54C6rAbTu0eFKNzQvprJLMhy0X/QRudsk mHNGt86axnUq3m2ePCiezRyZkg== X-Google-Smtp-Source: AA0mqf4pSdxpuNsvbAiQ/VPT4Uicb2yIOEyOj0DptBJEnqY46AvxjvE1jv4RoOcak7HL0HGEg3fM1Q== X-Received: by 2002:a05:6000:18cc:b0:236:6d79:b312 with SMTP id w12-20020a05600018cc00b002366d79b312mr805921wrq.699.1668161831083; Fri, 11 Nov 2022 02:17:11 -0800 (PST) Received: from localhost ([95.148.15.66]) by smtp.gmail.com with ESMTPSA id h8-20020a05600c2ca800b003b4a699ce8esm8500043wmc.6.2022.11.11.02.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 02:17:10 -0800 (PST) From: Punit Agrawal To: Yicong Yang Cc: , , , , , , , , , , , , , , , , , , , , , , , , , Barry Song <21cnbao@gmail.com>, , , Subject: Re: [External] [PATCH v5 0/2] arm64: support batched/deferred tlb shootdown during page reclamation References: <20221028081255.19157-1-yangyicong@huawei.com> Date: Fri, 11 Nov 2022 10:17:09 +0000 In-Reply-To: <20221028081255.19157-1-yangyicong@huawei.com> (Yicong Yang's message of "Fri, 28 Oct 2022 16:12:53 +0800") Message-ID: <87pmdtztga.fsf@stealth> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Yicong Yang writes: > From: Yicong Yang > > Though ARM64 has the hardware to do tlb shootdown, the hardware > broadcasting is not free. > A simplest micro benchmark shows even on snapdragon 888 with only > 8 cores, the overhead for ptep_clear_flush is huge even for paging > out one page mapped by only one process: > 5.36% a.out [kernel.kallsyms] [k] ptep_clear_flush > > While pages are mapped by multiple processes or HW has more CPUs, > the cost should become even higher due to the bad scalability of > tlb shootdown. > > The same benchmark can result in 16.99% CPU consumption on ARM64 > server with around 100 cores according to Yicong's test on patch > 4/4. > > This patchset leverages the existing BATCHED_UNMAP_TLB_FLUSH by > 1. only send tlbi instructions in the first stage - > arch_tlbbatch_add_mm() > 2. wait for the completion of tlbi by dsb while doing tlbbatch > sync in arch_tlbbatch_flush() > Testing on snapdragon shows the overhead of ptep_clear_flush > is removed by the patchset. The micro benchmark becomes 5% faster > even for one page mapped by single process on snapdragon 888. > > With this support we're possible to do more optimization for memory > reclamation and migration[*]. I applied the patches on v6.1-rc4 and was able to see the drop in ptep_clear_flush() in the perf report when running the test program from Patch 2. The tests were done on a rk3399 based system with benefits visible when running the tests on either of the clusters. So, for the series, Tested-by: Punit Agrawal Thanks, Punit [...]