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 EC32EC001E0 for ; Wed, 16 Aug 2023 16:23:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344647AbjHPQWs (ORCPT ); Wed, 16 Aug 2023 12:22:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344667AbjHPQWa (ORCPT ); Wed, 16 Aug 2023 12:22:30 -0400 Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E031C1; Wed, 16 Aug 2023 09:22:29 -0700 (PDT) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 9B0EF5C00A9; Wed, 16 Aug 2023 12:22:28 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Wed, 16 Aug 2023 12:22:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=devkernel.io; h= cc:cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1692202948; x=1692289348; bh=ls RtaTNVobWQ1QYQuf1PXHLidC8c/K56+tUwFDf+W1s=; b=LweUZTQitbkPkyPv+P AUoeEO8q8DAWpXFs39CnFzS0yPT6yEdBYwSfaj2UFCwQVPDLNAA14DA5Nlk6Il7m FvLQawh57P75apVu662fOa9r3u29VKtDuJVLA26KOzH2icptGh1VTG5suki6yKUJ SH6bWLRYlMKAzOT8s0xdTZjDOJ7s/hUZcZVBG46GNdIHjCpMwmUsYIUUUkkYVwwT cvbSVdYTFdAXZXK3fUffKaiRF1R2XBJe5qfEp4NwYgWEAL5ZiZkPf6/ArNd/cIPu kDV3zujGlvKY2tVFLeOWroVlW6hV2sePmB7dSRFhYQjOGBkpD82b/XgS8LNuk9+z 33bg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; t=1692202948; x=1692289348; bh=lsRtaTNVobWQ1 QYQuf1PXHLidC8c/K56+tUwFDf+W1s=; b=fVPFI/k3HxbxqvvKOssjyYK/I8/tY y7cXXizRSmm4/xoqgsHRIIoGrxUk+jDfy3gycjySI7yyd3CVSc+eFzk42d2AdeDp xzPrx7cCqfsf4LPCuRNqDCGKXzFvI5QrDgfPMfhIBdjgQyd76KuqDLkM0b0sZWWj xYV5jPfoDBcJ/VvABK8yO7OUqtR3LEcOOTX8Liwm2NecBoYma5sNYdMlvPat+oIs PinrrWQcuJf8IoNC8w3GZVzuYMA1G7y0xgxtp+ozaI5t3WutIGInXJGFeAR28mHG dMEVYHelmeSQQxVKGL/xS6r2NetrcG9tO34VcP9bcxhIy7RnsZoWV1+Aw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedruddtledguddtudcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpehffgfhvfevufffjgfkgggtsehttdfotddtredtnecuhfhrohhmpefuthgv fhgrnhcutfhovghstghhuceoshhhrhesuggvvhhkvghrnhgvlhdrihhoqeenucggtffrrg htthgvrhhnpeefledufefhgedvffeiuefhvddutedvteefgfeigeffudfhgeffueduveek ieeuudenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hshhhrseguvghvkhgvrhhnvghlrdhioh X-ME-Proxy: Feedback-ID: i84614614:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 16 Aug 2023 12:22:27 -0400 (EDT) References: <20230811162803.1361989-1-shr@devkernel.io> <43d64aee-4bd9-bba0-9434-55cec26bd9dc@redhat.com> User-agent: mu4e 1.10.1; emacs 28.2.50 From: Stefan Roesch To: David Hildenbrand Cc: kernel-team@fb.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2] proc/ksm: add ksm stats to /proc/pid/smaps Date: Wed, 16 Aug 2023 09:22:03 -0700 In-reply-to: Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org David Hildenbrand writes: > On 15.08.23 19:10, Stefan Roesch wrote: >> David Hildenbrand writes: >> >>> Sorry for the late reply, Gmail once again decided to classify your mails as >>> spam (for whatever reason). >>> >>> On 11.08.23 18:28, Stefan Roesch wrote: >>>> With madvise and prctl KSM can be enabled for different VMA's. Once it >>>> is enabled we can query how effective KSM is overall. However we cannot >>>> easily query if an individual VMA benefits from KSM. >>>> This commit adds a KSM section to the /prod//smaps file. It reports >>>> how many of the pages are KSM pages. >>>> Here is a typical output: >>>> 7f420a000000-7f421a000000 rw-p 00000000 00:00 0 >>>> Size: 262144 kB >>>> KernelPageSize: 4 kB >>>> MMUPageSize: 4 kB >>>> Rss: 51212 kB >>>> Pss: 8276 kB >>>> Shared_Clean: 172 kB >>>> Shared_Dirty: 42996 kB >>>> Private_Clean: 196 kB >>>> Private_Dirty: 7848 kB >>>> Referenced: 15388 kB >>>> Anonymous: 51212 kB >>>> KSM: 41376 kB >>>> LazyFree: 0 kB >>>> AnonHugePages: 0 kB >>>> ShmemPmdMapped: 0 kB >>>> FilePmdMapped: 0 kB >>>> Shared_Hugetlb: 0 kB >>>> Private_Hugetlb: 0 kB >>>> Swap: 202016 kB >>>> SwapPss: 3882 kB >>>> Locked: 0 kB >>>> THPeligible: 0 >>>> ProtectionKey: 0 >>>> ksm_state: 0 >>>> ksm_skip_base: 0 >>>> ksm_skip_count: 0 >>>> VmFlags: rd wr mr mw me nr mg anon >>>> This information also helps with the following workflow: >>>> - First enable KSM for all the VMA's of a process with prctl. >>>> - Then analyze with the above smaps report which VMA's benefit the most >>>> - Change the application (if possible) to add the corresponding madvise >>>> calls for the VMA's that benefit the most >>>> Signed-off-by: Stefan Roesch >>>> --- >>>> Documentation/filesystems/proc.rst | 3 +++ >>>> fs/proc/task_mmu.c | 5 +++++ >>>> 2 files changed, 8 insertions(+) >>>> diff --git a/Documentation/filesystems/proc.rst >>>> b/Documentation/filesystems/proc.rst >>>> index 7897a7dafcbc..4ef3c0bbf16a 100644 >>>> --- a/Documentation/filesystems/proc.rst >>>> +++ b/Documentation/filesystems/proc.rst >>>> @@ -461,6 +461,7 @@ Memory Area, or VMA) there is a series of lines such as the following:: >>>> Private_Dirty: 0 kB >>>> Referenced: 892 kB >>>> Anonymous: 0 kB >>>> + KSM: 0 kB >>>> LazyFree: 0 kB >>>> AnonHugePages: 0 kB >>>> ShmemPmdMapped: 0 kB >>>> @@ -501,6 +502,8 @@ accessed. >>>> a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE >>>> and a page is modified, the file page is replaced by a private anonymous copy. >>>> +"KSM" shows the amount of anonymous memory that has been de-duplicated. >>> >>> >>> How do we want to treat memory that has been deduplicated into the shared >>> zeropage? >>> >>> It would also match this description. >>> >>> See in mm-stable: >>> >>> commit 30ff6ed9a65c7e73545319fc15f7bcf9c52457eb >>> Author: xu xin >>> Date: Tue Jun 13 11:09:28 2023 +0800 >>> >>> ksm: support unsharing KSM-placed zero pages >>> >>> Patch series "ksm: support tracking KSM-placed zero-pages", v10. >> I see two approaches how to deal with zero page: >> - If zero page is not enabled, it works as is >> - If enabled >> - Document that zero page is accounted for the current vma or >> - Pass in the pte from smaps_pte_entry() to smaps_account() so we can >> determine if this is a zero page. > > That's probably the right thing to do: make the stat return the same value > independent of the usage of the shared zeropage. > I'll update the documentation accordingly. >> I'm not sure what to do about smaps_pmd_entry in that case. We >> probably don't care about compund pages. > > No, KSM only places the shared zeropage for PTEs, no need to handle PMDs.