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[2620:137:e000::1:20]) by mx.google.com with ESMTP id j64-20020a638b43000000b00563e7aa7e3asi6118021pge.873.2023.08.09.00.54.32; Wed, 09 Aug 2023 00:54:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=AIfFg+hw; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=collabora.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231197AbjHIGQt (ORCPT + 99 others); Wed, 9 Aug 2023 02:16:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231138AbjHIGQo (ORCPT ); Wed, 9 Aug 2023 02:16:44 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40C5A1FEA; Tue, 8 Aug 2023 23:16:35 -0700 (PDT) Received: from localhost.localdomain (unknown [59.103.218.230]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: usama.anjum) by madras.collabora.co.uk (Postfix) with ESMTPSA id 96DB566071B0; Wed, 9 Aug 2023 07:16:28 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1691561794; bh=d1JzgXg4it2dCo40JY/rVCAzdGTdQgXd73Ed8NneIJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AIfFg+hwomA6kJQ+/JBDTwe+MUKcElOB/asCqG5r5ymzocPhDA8EpyfVwu6vPedGH AqiRsRHT0SdaFo38dPgrD7e3IOoB4mjRzdxY/rUD2nOLteO1zLdxr9zVzSKaEbQ8iU NDsAsCOkbl7swLM1pmaXJtPNxQF8Y4OOtQyMAsyXEUD9tEIXRjRGJAwWpqtAstrDm2 Vd0ili0WhU5ag1TXV2+GBEr0moPF/PiHekR7mciB3A0psNAcy0ItsCMCI19PPKSr5W t7G4S6lrUO6Kd3KdVn52Fm8O5Jqs2CALuCsu3sV1JOZvCiXaLOoj53ZcPVLd0FhvGN rzz1EPAlimj5w== From: Muhammad Usama Anjum To: Peter Xu , David Hildenbrand , Andrew Morton , =?utf-8?b?TWljaGHFgiBNaXJvc8WC?= =?utf-8?b?YXc=?= , Andrei Vagin , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Mike Rapoport , Nadav Amit Cc: Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Muhammad Usama Anjum , Matthew Wilcox , Pasha Tatashin , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: [PATCH v28 3/6] fs/proc/task_mmu: Add fast paths to get/clear PAGE_IS_WRITTEN flag Date: Wed, 9 Aug 2023 11:16:00 +0500 Message-Id: <20230809061603.1969154-4-usama.anjum@collabora.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230809061603.1969154-1-usama.anjum@collabora.com> References: <20230809061603.1969154-1-usama.anjum@collabora.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773737279600577123 X-GMAIL-MSGID: 1773737279600577123 Adding fast code paths to handle specifically only get and/or clear operation of PAGE_IS_WRITTEN, increases its performance by 0-35%. The results of some test cases are given below: Test-case-1 t1 = (Get + WP) time t2 = WP time t1 t2 Without this patch: 140-170mcs 90-115mcs With this patch: 110mcs 80mcs Worst case diff: 35% faster 30% faster Test-case-2 t3 = atomic Get and WP t3 Without this patch: 120-140mcs With this patch: 100-110mcs Worst case diff: 21% faster Signed-off-by: Muhammad Usama Anjum --- The test to measure the performance can be found: https://is.gd/FtSKcD 8 8192 3 1 0 and 8 8192 3 1 1 arguments have been used to produce the above mentioned results. --- fs/proc/task_mmu.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 0e219a44e97cd..e336ec0151185 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2107,6 +2107,43 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start, return 0; } + if (!p->vec_out) { + /* Fast path for performing exclusive WP */ + for (addr = start; addr != end; pte++, addr += PAGE_SIZE) { + if (pte_uffd_wp(ptep_get(pte))) + continue; + make_uffd_wp_pte(vma, addr, pte); + if (!flush) { + start = addr; + flush = true; + } + } + goto flush_and_return; + } + + if (!p->arg.category_anyof_mask && !p->arg.category_inverted && + p->arg.category_mask == PAGE_IS_WRITTEN && + p->arg.return_mask == PAGE_IS_WRITTEN) { + for (addr = start; addr < end; pte++, addr += PAGE_SIZE) { + unsigned long next = addr + PAGE_SIZE; + + if (pte_uffd_wp(ptep_get(pte))) + continue; + ret = pagemap_scan_output(p->cur_vma_category | PAGE_IS_WRITTEN, + p, addr, &next); + if (next == addr) + break; + if (~p->arg.flags & PM_SCAN_WP_MATCHING) + continue; + make_uffd_wp_pte(vma, addr, pte); + if (!flush) { + start = addr; + flush = true; + } + } + goto flush_and_return; + } + for (addr = start; addr != end; pte++, addr += PAGE_SIZE) { unsigned long categories = p->cur_vma_category | pagemap_page_category(p, vma, addr, ptep_get(pte)); @@ -2131,6 +2168,7 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start, } } +flush_and_return: if (flush) flush_tlb_range(vma, start, addr);