From patchwork Mon Aug 22 08:21:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 12950359 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B38FEC32793 for ; Mon, 22 Aug 2022 08:40:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Ecuay0vio6HBFIP7EXnhSt+B5mXJYIGylUuxuddJZ68=; b=4ptMGa14lIeIGa E/WiL996XalPcIZa1B/6xYY4ZR8hwbUjP5mKUCZzfjjTxjBJ9NBw6/IXaS5KJgl/qJ9O0IvEC6/Uy qiL0qqUAetc85J2ocOarHy85bBrsOeFp6muyrFHb8N9xHQifQwd/RF3/dmKsQ4gJ7eUEB4tbhdQto gVwxHgFJtxLxM2sl+g+7mpKIkDG+rfK+NpXaBwwbaJlKsbgBF6XY+tHv52ERNx9VZr+qGbvtiicBP TPsVu8zb4TNEFWNDZEhO0BESU/7XrKKQ1Vzs9EP4D+cL/i0t6pCwYtWPwnyTrvRBOsvPyhE6Ao8Qw CzG1kzaGw4V6j5S1s+pA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2xx-006Ytw-R6; Mon, 22 Aug 2022 08:39:26 +0000 Received: from szxga08-in.huawei.com ([45.249.212.255]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2if-006QGc-Eg; Mon, 22 Aug 2022 08:23:44 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4MB4zR2LXtz1N7HW; Mon, 22 Aug 2022 16:20:03 +0800 (CST) Received: from localhost.localdomain (10.67.164.66) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 22 Aug 2022 16:23:30 +0800 From: Yicong Yang To: , , , , , , CC: , , , , , , , , , , , , , , , , Barry Song <21cnbao@gmail.com>, , , , , Barry Song Subject: [PATCH v3 1/4] Revert "Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64" Date: Mon, 22 Aug 2022 16:21:17 +0800 Message-ID: <20220822082120.8347-2-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220822082120.8347-1-yangyicong@huawei.com> References: <20220822082120.8347-1-yangyicong@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220822_012338_172702_D9D2481C X-CRM114-Status: GOOD ( 11.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Barry Song This reverts commit 6bfef171d0d74cb050112e0e49feb20bfddf7f42. I was wrong. Though ARM64 has hardware TLB flush, but it is not free and it is still expensive. We still have a good chance to enable batched and deferred TLB flush on ARM64 for memory reclamation. A possible way is that we only queue tlbi instructions in hardware's queue. When we have to broadcast TLB, we broadcast it by dsb. We just need to get adapted the existing BATCHED_UNMAP_TLB_FLUSH. Tested-by: Xin Hao Signed-off-by: Barry Song Signed-off-by: Yicong Yang --- Documentation/features/arch-support.txt | 1 - Documentation/features/vm/TLB/arch-support.txt | 2 +- 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/Documentation/features/arch-support.txt b/Documentation/features/arch-support.txt index 118ae031840b..d22a1095e661 100644 --- a/Documentation/features/arch-support.txt +++ b/Documentation/features/arch-support.txt @@ -8,5 +8,4 @@ The meaning of entries in the tables is: | ok | # feature supported by the architecture |TODO| # feature not yet supported by the architecture | .. | # feature cannot be supported by the hardware - | N/A| # feature doesn't apply to the architecture diff --git a/Documentation/features/vm/TLB/arch-support.txt b/Documentation/features/vm/TLB/arch-support.txt index 039e4e91ada3..1c009312b9c1 100644 --- a/Documentation/features/vm/TLB/arch-support.txt +++ b/Documentation/features/vm/TLB/arch-support.txt @@ -9,7 +9,7 @@ | alpha: | TODO | | arc: | TODO | | arm: | TODO | - | arm64: | N/A | + | arm64: | TODO | | csky: | TODO | | hexagon: | TODO | | ia64: | TODO | From patchwork Mon Aug 22 08:21:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 12950357 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 93278C28D13 for ; Mon, 22 Aug 2022 08:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YmpQX5d6h41ZLKaNMnUXuP7r7d/L/7tluGeY5ZZgh1I=; b=CCdtm0UhFa7SPZ zKXNPlA6iM7Nl462Msanm4qMB/clyf12Lqd5g/9rD8BKLXNPLJ/FxD99jbf7HmVufG6MDxDsIamGQ VkHqED/dMKwZ96ANOVQaJNqcLkBY4vqr853R1liM6QJHiLrZx5oGtTdczAWcx/9DacJ7NxP9/5J1G QST3+8wZDsOspOGoqFwD8s9bNEr8vBV8txw1TelHVdNC1MoI7uxlU3EwbrB4ydoLniIHdKT5uMb3f OJlkikdg1i/RLoojhx5pR4BCP4Fg2Kqk/B/h8UsuQx+OtNaGXE/h6NPDChMyGsmH8q3+oFclVtZP5 c8E90OdPrZcrdL/N0BWA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2wL-006Y3T-SE; Mon, 22 Aug 2022 08:37:46 +0000 Received: from szxga08-in.huawei.com ([45.249.212.255]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2if-006QGb-Do; Mon, 22 Aug 2022 08:23:45 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4MB4zR4wk3z1N7Vq; Mon, 22 Aug 2022 16:20:03 +0800 (CST) Received: from localhost.localdomain (10.67.164.66) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 22 Aug 2022 16:23:30 +0800 From: Yicong Yang To: , , , , , , CC: , , , , , , , , , , , , , , , , Barry Song <21cnbao@gmail.com>, , , , , Anshuman Khandual Subject: [PATCH v3 2/4] mm/tlbbatch: Introduce arch_tlbbatch_should_defer() Date: Mon, 22 Aug 2022 16:21:18 +0800 Message-ID: <20220822082120.8347-3-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220822082120.8347-1-yangyicong@huawei.com> References: <20220822082120.8347-1-yangyicong@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220822_012337_989974_82E41FBD X-CRM114-Status: GOOD ( 10.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Anshuman Khandual The entire scheme of deferred TLB flush in reclaim path rests on the fact that the cost to refill TLB entries is less than flushing out individual entries by sending IPI to remote CPUs. But architecture can have different ways to evaluate that. Hence apart from checking TTU_BATCH_FLUSH in the TTU flags, rest of the decision should be architecture specific. Signed-off-by: Anshuman Khandual [https://lore.kernel.org/linuxppc-dev/20171101101735.2318-2-khandual@linux.vnet.ibm.com/] Signed-off-by: Yicong Yang [Rebase and fix incorrect return value type] Reviewed-by: Kefeng Wang Reviewed-by: Anshuman Khandual --- arch/x86/include/asm/tlbflush.h | 12 ++++++++++++ mm/rmap.c | 9 +-------- 2 files changed, 13 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index cda3118f3b27..8a497d902c16 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -240,6 +240,18 @@ static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a) flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false); } +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm) +{ + bool should_defer = false; + + /* If remote CPUs need to be flushed then defer batch the flush */ + if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) + should_defer = true; + put_cpu(); + + return should_defer; +} + static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) { /* diff --git a/mm/rmap.c b/mm/rmap.c index edc06c52bc82..a17a004550c6 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -687,17 +687,10 @@ static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) */ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) { - bool should_defer = false; - if (!(flags & TTU_BATCH_FLUSH)) return false; - /* If remote CPUs need to be flushed then defer batch the flush */ - if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) - should_defer = true; - put_cpu(); - - return should_defer; + return arch_tlbbatch_should_defer(mm); } /* From patchwork Mon Aug 22 08:21:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 12950355 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9026EC28D13 for ; Mon, 22 Aug 2022 08:37:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=iukRtzhCwm/3Rkug8R1dcgwI/34iiEW5pPse+7tZJnw=; b=zR7hEBm08GhsqH aW2JMVrO0Qq1jRWmefImP2awRxkkoecs3rhaMjFuI6jdmpZSdPlft9fme78NL+DEbk44sey7DSC96 r85BlahKmA44uPN48eXmO4pLWR6KLyTMaspE9dRjQMxf4ILnN/1MbLmtU/FCDJkA8QhbJOEHwFrQ5 kLzdTe/X/F4e+LSBaq8qnSFdDf+8WWwRJZsgXRRPfj8hmtI54U4SqtZC08dgHcwYkaCLxBQHtbMrJ vIyuKx7NijLQytDA1b/PjBCxk+SVq5EQ0XzVN8k/WVzHgf6Yfgr4TaLALcRzuJBQ5PCu+Ra/73SQN JSTZT3UQI8G01HQx50Hg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2uS-006X4Z-6X; Mon, 22 Aug 2022 08:35:49 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2ic-006QFv-Bi; Mon, 22 Aug 2022 08:23:37 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MB4yW0hwhzXdwW; Mon, 22 Aug 2022 16:19:15 +0800 (CST) Received: from localhost.localdomain (10.67.164.66) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 22 Aug 2022 16:23:30 +0800 From: Yicong Yang To: , , , , , , CC: , , , , , , , , , , , , , , , , Barry Song <21cnbao@gmail.com>, , , , , Barry Song , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Nadav Amit , Mel Gorman Subject: [PATCH v3 3/4] mm: rmap: Extend tlbbatch APIs to fit new platforms Date: Mon, 22 Aug 2022 16:21:19 +0800 Message-ID: <20220822082120.8347-4-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220822082120.8347-1-yangyicong@huawei.com> References: <20220822082120.8347-1-yangyicong@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220822_012334_821220_2D53B4AC X-CRM114-Status: GOOD ( 11.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Barry Song Add uaddr to tlbbatch APIs so that platforms like ARM64 are able to apply this on their specific hardware features. For ARM64, this could be sending tlbi into hardware queues for the page with this particular uaddr. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Nadav Amit Cc: Mel Gorman Tested-by: Xin Hao Signed-off-by: Barry Song Signed-off-by: Yicong Yang Reviewed-by: Kefeng Wang --- arch/x86/include/asm/tlbflush.h | 3 ++- mm/rmap.c | 10 ++++++---- 2 files changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 8a497d902c16..5bd78ae55cd4 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -264,7 +264,8 @@ static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) } static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch, - struct mm_struct *mm) + struct mm_struct *mm, + unsigned long uaddr) { inc_mm_tlb_gen(mm); cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm)); diff --git a/mm/rmap.c b/mm/rmap.c index a17a004550c6..7187a72b63b1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -642,12 +642,13 @@ void try_to_unmap_flush_dirty(void) #define TLB_FLUSH_BATCH_PENDING_LARGE \ (TLB_FLUSH_BATCH_PENDING_MASK / 2) -static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) +static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable, + unsigned long uaddr) { struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; int batch, nbatch; - arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); + arch_tlbbatch_add_mm(&tlb_ubc->arch, mm, uaddr); tlb_ubc->flush_required = true; /* @@ -725,7 +726,8 @@ void flush_tlb_batched_pending(struct mm_struct *mm) } } #else -static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) +static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable, + unsigned long uaddr) { } @@ -1587,7 +1589,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, */ pteval = ptep_get_and_clear(mm, address, pvmw.pte); - set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); + set_tlb_ubc_flush_pending(mm, pte_dirty(pteval), address); } else { pteval = ptep_clear_flush(vma, address, pvmw.pte); } From patchwork Mon Aug 22 08:21:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 12950356 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 4C9C1C28D13 for ; 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Mon, 22 Aug 2022 08:36:41 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQ2ic-006QGd-Hh; Mon, 22 Aug 2022 08:23:39 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MB4zm2lylzlWHZ; Mon, 22 Aug 2022 16:20:20 +0800 (CST) Received: from localhost.localdomain (10.67.164.66) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 22 Aug 2022 16:23:31 +0800 From: Yicong Yang To: , , , , , , CC: , , , , , , , , , , , , , , , , Barry Song <21cnbao@gmail.com>, , , , , Barry Song , Nadav Amit , Mel Gorman Subject: [PATCH v3 4/4] arm64: support batched/deferred tlb shootdown during page reclamation Date: Mon, 22 Aug 2022 16:21:20 +0800 Message-ID: <20220822082120.8347-5-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220822082120.8347-1-yangyicong@huawei.com> References: <20220822082120.8347-1-yangyicong@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220822_012335_242656_CF665A88 X-CRM114-Status: GOOD ( 21.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Barry Song on x86, batched and deferred tlb shootdown has lead to 90% performance increase on tlb shootdown. on arm64, HW can do tlb shootdown without software IPI. But sync tlbi is still quite expensive. Even running a simplest program which requires swapout can prove this is true, #include #include #include #include int main() { #define SIZE (1 * 1024 * 1024) volatile unsigned char *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); memset(p, 0x88, SIZE); for (int k = 0; k < 10000; k++) { /* swap in */ for (int i = 0; i < SIZE; i += 4096) { (void)p[i]; } /* swap out */ madvise(p, SIZE, MADV_PAGEOUT); } } Perf result on snapdragon 888 with 8 cores by using zRAM as the swap block device. ~ # perf record taskset -c 4 ./a.out [ perf record: Woken up 10 times to write data ] [ perf record: Captured and wrote 2.297 MB perf.data (60084 samples) ] ~ # perf report # To display the perf.data header info, please use --header/--header-only options. # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 60K of event 'cycles' # Event count (approx.): 35706225414 # # Overhead Command Shared Object Symbol # ........ ....... ................. ............................................................................. # 21.07% a.out [kernel.kallsyms] [k] _raw_spin_unlock_irq 8.23% a.out [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore 6.67% a.out [kernel.kallsyms] [k] filemap_map_pages 6.16% a.out [kernel.kallsyms] [k] __zram_bvec_write 5.36% a.out [kernel.kallsyms] [k] ptep_clear_flush 3.71% a.out [kernel.kallsyms] [k] _raw_spin_lock 3.49% a.out [kernel.kallsyms] [k] memset64 1.63% a.out [kernel.kallsyms] [k] clear_page 1.42% a.out [kernel.kallsyms] [k] _raw_spin_unlock 1.26% a.out [kernel.kallsyms] [k] mod_zone_state.llvm.8525150236079521930 1.23% a.out [kernel.kallsyms] [k] xas_load 1.15% a.out [kernel.kallsyms] [k] zram_slot_lock ptep_clear_flush() takes 5.36% CPU in the micro-benchmark swapping in/out a page mapped by only one process. If the page is mapped by multiple processes, typically, like more than 100 on a phone, the overhead would be much higher as we have to run tlb flush 100 times for one single page. Plus, tlb flush overhead will increase with the number of CPU cores due to the bad scalability of tlb shootdown in HW, so those ARM64 servers should expect much higher overhead. Further perf annonate shows 95% cpu time of ptep_clear_flush is actually used by the final dsb() to wait for the completion of tlb flush. This provides us a very good chance to leverage the existing batched tlb in kernel. The minimum modification is that we only send async tlbi in the first stage and we send dsb while we have to sync in the second stage. With the above simplest micro benchmark, collapsed time to finish the program decreases around 5%. Typical collapsed time w/o patch: ~ # time taskset -c 4 ./a.out 0.21user 14.34system 0:14.69elapsed w/ patch: ~ # time taskset -c 4 ./a.out 0.22user 13.45system 0:13.80elapsed Also, Yicong Yang added the following observation. Tested with benchmark in the commit on Kunpeng920 arm64 server, observed an improvement around 12.5% with command `time ./swap_bench`. w/o w/ real 0m13.460s 0m11.771s user 0m0.248s 0m0.279s sys 0m12.039s 0m11.458s Originally it's noticed a 16.99% overhead of ptep_clear_flush() which has been eliminated by this patch: [root@localhost yang]# perf record -- ./swap_bench && perf report [...] 16.99% swap_bench [kernel.kallsyms] [k] ptep_clear_flush Cc: Jonathan Corbet Cc: Nadav Amit Cc: Mel Gorman Tested-by: Yicong Yang Tested-by: Xin Hao Signed-off-by: Barry Song Signed-off-by: Yicong Yang Reviewed-by: Kefeng Wang --- .../features/vm/TLB/arch-support.txt | 2 +- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/tlbbatch.h | 12 ++++++++ arch/arm64/include/asm/tlbflush.h | 28 +++++++++++++++++-- 4 files changed, 40 insertions(+), 3 deletions(-) create mode 100644 arch/arm64/include/asm/tlbbatch.h diff --git a/Documentation/features/vm/TLB/arch-support.txt b/Documentation/features/vm/TLB/arch-support.txt index 1c009312b9c1..2caf815d7c6c 100644 --- a/Documentation/features/vm/TLB/arch-support.txt +++ b/Documentation/features/vm/TLB/arch-support.txt @@ -9,7 +9,7 @@ | alpha: | TODO | | arc: | TODO | | arm: | TODO | - | arm64: | TODO | + | arm64: | ok | | csky: | TODO | | hexagon: | TODO | | ia64: | TODO | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 571cc234d0b3..09d45cd6d665 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -93,6 +93,7 @@ config ARM64 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 select ARCH_SUPPORTS_NUMA_BALANCING select ARCH_SUPPORTS_PAGE_TABLE_CHECK + select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT select ARCH_WANT_DEFAULT_BPF_JIT select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT diff --git a/arch/arm64/include/asm/tlbbatch.h b/arch/arm64/include/asm/tlbbatch.h new file mode 100644 index 000000000000..fedb0b87b8db --- /dev/null +++ b/arch/arm64/include/asm/tlbbatch.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ARCH_ARM64_TLBBATCH_H +#define _ARCH_ARM64_TLBBATCH_H + +struct arch_tlbflush_unmap_batch { + /* + * For arm64, HW can do tlb shootdown, so we don't + * need to record cpumask for sending IPI + */ +}; + +#endif /* _ARCH_ARM64_TLBBATCH_H */ diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h index 412a3b9a3c25..23cbc987321a 100644 --- a/arch/arm64/include/asm/tlbflush.h +++ b/arch/arm64/include/asm/tlbflush.h @@ -254,17 +254,24 @@ static inline void flush_tlb_mm(struct mm_struct *mm) dsb(ish); } -static inline void flush_tlb_page_nosync(struct vm_area_struct *vma, + +static inline void __flush_tlb_page_nosync(struct mm_struct *mm, unsigned long uaddr) { unsigned long addr; dsb(ishst); - addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm)); + addr = __TLBI_VADDR(uaddr, ASID(mm)); __tlbi(vale1is, addr); __tlbi_user(vale1is, addr); } +static inline void flush_tlb_page_nosync(struct vm_area_struct *vma, + unsigned long uaddr) +{ + return __flush_tlb_page_nosync(vma->vm_mm, uaddr); +} + static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr) { @@ -272,6 +279,23 @@ static inline void flush_tlb_page(struct vm_area_struct *vma, dsb(ish); } +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm) +{ + return true; +} + +static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch, + struct mm_struct *mm, + unsigned long uaddr) +{ + __flush_tlb_page_nosync(mm, uaddr); +} + +static inline void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch) +{ + dsb(ish); +} + /* * This is meant to avoid soft lock-ups on large TLB flushing ranges and not * necessarily a performance improvement.