From patchwork Thu Feb 15 10:32:03 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13557930 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 5C589C48BF0 for ; Thu, 15 Feb 2024 10:34:10 +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=FCIW49dDshgwOVlzx/hyNunOeuub4rpGHFJstazJcv4=; b=AmdeNalIh9/bEd xd1TzD9peEJKsURDF9mF1lP73eeK4i609sU3Il7/VkOTzoYNH6UfaiDQ7Kpq01HZDVGUumJcVwl0F twRbhIgzYZ/PKd36zJ6qiAstEGYnzILpCudGu6X0uOVVHjTOBYCY9AHDrvyD8FEJrTRelWcLlmP1l SQkRKDOthfu03r5VKcEo03xDl62qMWudLkGH8t/jv0KrTK0pPz1v+r4Cg034JVTD1ZfBuBScieiTH fh+Q8vSX12gndIGHy84Mh8d/6t70iu25lDHD40PghgDi0wLNecWBMFwUcfnAu3Pl/Gs13ubHE09MT xhAXurB0A10TlXBhM48g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1raZ3x-0000000Fmk9-2tLh; Thu, 15 Feb 2024 10:33:53 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1raZ3T-0000000FmPS-13wh for linux-arm-kernel@bombadil.infradead.org; Thu, 15 Feb 2024 10:33:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=RBDSb1ynAOyzexiyHHWXWWE26cJncrKBIu2RWSUrpHs=; b=VfQJKqARhQwqs05+R02qcYhyoq Mty0xinqIsjQ0ZYS+h52s3vRUg+dfiZUMzZpomZ0PuT1zmwjZSoEgqTSGtkR75JYU2eX4AqZS2CS3 Ju5M3o0TUaMVC0zqUJWgJys2I6pJ2NP6D+kcsoATnWRIs66ZK/L8s+vifVm2bdi3ngv1xovClsAus EyYvXhsz8/Z9f4JQLCBxXblNA5VciDp+NXrwx9InqF9FYW7b1ut67fEOQNIzX+rvAfvz3t/cT8FDJ EnolKr0z8eKCqV/XUH/wMhbk2S1dm092WH9MDuH289leV2pd85tK0HDR6nXsAzrUCoDzeC5wKQNDc 7kz1W/uw==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1raZ3L-0000000GfRo-21lv for linux-arm-kernel@lists.infradead.org; Thu, 15 Feb 2024 10:33:19 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 871BF15BF; Thu, 15 Feb 2024 02:33:55 -0800 (PST) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7B9B93F7B4; Thu, 15 Feb 2024 02:33:11 -0800 (PST) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Ard Biesheuvel , Marc Zyngier , James Morse , Andrey Ryabinin , Andrew Morton , Matthew Wilcox , Mark Rutland , David Hildenbrand , Kefeng Wang , John Hubbard , Zi Yan , Barry Song <21cnbao@gmail.com>, Alistair Popple , Yang Shi , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 16/18] arm64/mm: Implement pte_batch_hint() Date: Thu, 15 Feb 2024 10:32:03 +0000 Message-Id: <20240215103205.2607016-17-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240215103205.2607016-1-ryan.roberts@arm.com> References: <20240215103205.2607016-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240215_103317_391649_91F4FF4D X-CRM114-Status: GOOD ( 12.58 ) 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 When core code iterates over a range of ptes and calls ptep_get() for each of them, if the range happens to cover contpte mappings, the number of pte reads becomes amplified by a factor of the number of PTEs in a contpte block. This is because for each call to ptep_get(), the implementation must read all of the ptes in the contpte block to which it belongs to gather the access and dirty bits. This causes a hotspot for fork(), as well as operations that unmap memory such as munmap(), exit and madvise(MADV_DONTNEED). Fortunately we can fix this by implementing pte_batch_hint() which allows their iterators to skip getting the contpte tail ptes when gathering the batch of ptes to operate on. This results in the number of PTE reads returning to 1 per pte. Acked-by: Mark Rutland Reviewed-by: David Hildenbrand Tested-by: John Hubbard Signed-off-by: Ryan Roberts Acked-by: Catalin Marinas --- arch/arm64/include/asm/pgtable.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index a8f1a35e3086..d759a20d2929 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -1213,6 +1213,15 @@ static inline void contpte_try_unfold(struct mm_struct *mm, unsigned long addr, __contpte_try_unfold(mm, addr, ptep, pte); } +#define pte_batch_hint pte_batch_hint +static inline unsigned int pte_batch_hint(pte_t *ptep, pte_t pte) +{ + if (!pte_valid_cont(pte)) + return 1; + + return CONT_PTES - (((unsigned long)ptep >> 3) & (CONT_PTES - 1)); +} + /* * The below functions constitute the public API that arm64 presents to the * core-mm to manipulate PTE entries within their page tables (or at least this