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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEA10C43441 for ; Fri, 23 Nov 2018 15:25:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9622E20685 for ; Fri, 23 Nov 2018 15:25:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9622E20685 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410109AbeKXCJm (ORCPT ); Fri, 23 Nov 2018 21:09:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:57982 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390948AbeKXCJl (ORCPT ); Fri, 23 Nov 2018 21:09:41 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 04200AC4C; Fri, 23 Nov 2018 15:25:04 +0000 (UTC) Subject: Re: [RFC PATCH 2/3] mm, thp, proc: report THP eligibility for each vma To: Michal Hocko Cc: linux-api@vger.kernel.org, Andrew Morton , Alexey Dobriyan , linux-mm@kvack.org, LKML References: <20181120103515.25280-1-mhocko@kernel.org> <20181120103515.25280-3-mhocko@kernel.org> <73b55240-d36c-cf97-d7fd-85e2ae1e9309@suse.cz> <20181123152136.GA5827@dhcp22.suse.cz> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSFWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmNvbT7CwZcEEwEKAEECGwMFCwkIBwMFFQoJCAsFFgIDAQAC HgECF4ACGQEWIQSpQNQ0mSwujpkQPVAiT6fnzIKmZAUCWi/zTwUJBbOLuQAKCRAiT6fnzIKm ZIpED/4jRN/6LKZZIT4R2xoou0nJkBGVA3nfb+mUMgi3uwn/zC+o6jjc3ShmP0LQ0cdeuSt/ t2ytstnuARTFVqZT4/IYzZgBsLM8ODFY5vGfPw00tsZMIfFuVPQX3xs0XgLEHw7/1ZCVyJVr mTzYmV3JruwhMdUvIzwoZ/LXjPiEx1MRdUQYHAWwUfsl8lUZeu2QShL3KubR1eH6lUWN2M7t VcokLsnGg4LTajZzZfq2NqCKEQMY3JkAmOu/ooPTrfHCJYMF/5dpi8YF1CkQF/PVbnYbPUuh dRM0m3NzPtn5DdyfFltJ7fobGR039+zoCo6dFF9fPltwcyLlt1gaItfX5yNbOjX3aJSHY2Vc A5T+XAVC2sCwj0lHvgGDz/dTsMM9Ob/6rRJANlJPRWGYk3WVWnbgW8UejCWtn1FkiY/L/4qJ UsqkId8NkkVdVAenCcHQmOGjRQYTpe6Cf4aQ4HGNDeWEm3H8Uq9vmHhXXcPLkxBLRbGDSHyq vUBVaK+dAwAsXn/5PlGxw1cWtur1ep7RDgG3vVQDhIOpAXAg6HULjcbWpBEFaoH720oyGmO5 kV+yHciYO3nPzz/CZJzP5Ki7Q1zqBb/U6gib2at5Ycvews+vTueYO+rOb9sfD8BFTK386LUK uce7E38owtgo/V2GV4LMWqVOy1xtCB6OAUfnGDU2EM7ATQRbGTU1AQgAn0H6UrFiWcovkh6E XVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQLa1PQDUi6j00ChlcR66g9/V0sPIcSutacPKf dKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMhFmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCT sTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sfbAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZO rIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq+aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahK tQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4njQARAQABwsF8BBgBCgAmFiEEqUDUNJksLo6Z ED1QIk+n58yCpmQFAlsZNTUCGwwFCQPCZwAACgkQIk+n58yCpmQ83g/9Frg1sRMdGPn98zV+ O2eC3h0p5f/oxxQ8MhG5znwHoW4JDG2TuxfcQuz7X7Dd5JWscjlw4VFJ2DD+IrDAGLHwPhCr RyfKalnrbYokvbClM9EuU1oUuh7k+Sg5ECNXEsamW9AiWGCaKWNDdHre3Lf4xl+RJWxghOVW RiUdpLA/a3yDvJNVr6rxkDHQ1P24ZZz/VKDyP+6g8aty2aWEU0YFNjI+rqYZb2OppDx6fdma YnLDcIfDFnkVlDmpznnGCyEqLLyMS3GH52AH13zMT9L9QYgT303+r6QQpKBIxAwn8Jg8dAlV OLhgeHXKr+pOQdFf6iu2sXlUR4MkO/5KWM1K0jFR2ug8Pb3aKOhowVMBT64G0TXhQ/kX4tZ2 ZF0QZLUCHU3Cigvbu4AWWVMNDEOGD/4sn9OoHxm6J04jLUHFUpFKDcjab4NRNWoHLsuLGjve Gdbr2RKO2oJ5qZj81K7os0/5vTAA4qHDP2EETAQcunTn6aPlkUnJ8aw6I1Rwyg7/XsU7gQHF IM/cUMuWWm7OUUPtJeR8loxZiZciU7SMvN1/B9ycPMFs/A6EEzyG+2zKryWry8k7G/pcPrFx O2PkDPy3YmN1RfpIX2HEmnCEFTTCsKgYORangFu/qOcXvM83N+2viXxG4mjLAMiIml1o2lKV cqmP8roqufIAj+Ohhzs= Message-ID: Date: Fri, 23 Nov 2018 16:24:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181123152136.GA5827@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/23/18 4:21 PM, Michal Hocko wrote: > On Fri 23-11-18 16:07:06, Vlastimil Babka wrote: >> On 11/20/18 11:35 AM, Michal Hocko wrote: >>> From: Michal Hocko >>> >>> Userspace falls short when trying to find out whether a specific memory >>> range is eligible for THP. There are usecases that would like to know >>> that >>> http://lkml.kernel.org/r/alpine.DEB.2.21.1809251248450.50347@chino.kir.corp.google.com >>> : This is used to identify heap mappings that should be able to fault thp >>> : but do not, and they normally point to a low-on-memory or fragmentation >>> : issue. >>> >>> The only way to deduce this now is to query for hg resp. nh flags and >>> confronting the state with the global setting. Except that there is >>> also PR_SET_THP_DISABLE that might change the picture. So the final >>> logic is not trivial. Moreover the eligibility of the vma depends on >>> the type of VMA as well. In the past we have supported only anononymous >>> memory VMAs but things have changed and shmem based vmas are supported >>> as well these days and the query logic gets even more complicated >>> because the eligibility depends on the mount option and another global >>> configuration knob. >>> >>> Simplify the current state and report the THP eligibility in >>> /proc//smaps for each existing vma. Reuse transparent_hugepage_enabled >>> for this purpose. The original implementation of this function assumes >>> that the caller knows that the vma itself is supported for THP so make >>> the core checks into __transparent_hugepage_enabled and use it for >>> existing callers. __show_smap just use the new transparent_hugepage_enabled >>> which also checks the vma support status (please note that this one has >>> to be out of line due to include dependency issues). >>> >>> Signed-off-by: Michal Hocko >> >> Not thrilled by this, > > Any specific concern? The kitchen sink that smaps slowly becomes, with associated overhead (i.e. one of reasons there's now smaps_rollup). Would be much nicer if userspace had some way to say which fields it's interested in. But I have no good ideas for that right now :/