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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 342F1C433EF for ; Fri, 13 May 2022 23:56:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8CEED8D0001; Fri, 13 May 2022 19:56:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 881086B0075; Fri, 13 May 2022 19:56:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F7DD8D0001; Fri, 13 May 2022 19:56:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 5E9846B0073 for ; Fri, 13 May 2022 19:56:13 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 39838605B1 for ; Fri, 13 May 2022 23:56:13 +0000 (UTC) X-FDA: 79462381026.13.4C3D546 Received: from mail-lf1-f44.google.com (mail-lf1-f44.google.com [209.85.167.44]) by imf04.hostedemail.com (Postfix) with ESMTP id 86135400C1 for ; Fri, 13 May 2022 23:56:01 +0000 (UTC) Received: by mail-lf1-f44.google.com with SMTP id p26so16961468lfh.10 for ; Fri, 13 May 2022 16:56:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=syKHni0X18bYxOVWezISkZYPuF909HTQzCRtMgkCjQA=; b=Y0Tb3kJJxT7ibE0dBP0o0QG2Izoo6vFyQZBZLfJMH38Tps0J561FddiX7f08XS81f1 F6QfaAEDgEMcXl9hiL22GB9jGd7KKFvwsIhirJKdXcTv97XEBrPdEZ8HG06UU+gY1v6f xIZ2wvqrIOtPmcIKP3M/4+wTHrUuoH06sgi8BWY1MldkR0MWnmemDcbu2HfqrkLYx4vz 7eDO76cytWwSYyjwaoxpIDcnRdMVOHea9Gm41js/GPTl2FC+cvqB7PCTHc0b2ieEf37v FhZPKpI0IvsZZ9v54DbAzEhmb73cOVFt9WZzncOkH3MJWWF4/XUliqnkPmVlg9QNFHdY QaHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=syKHni0X18bYxOVWezISkZYPuF909HTQzCRtMgkCjQA=; b=CqEXcB6ALbinzCic3A+icouCTPlwLdTBHM6VqzFfaFlzWVjK1ad84DnBvmGQEzp84K GOBr3AcDjiuIGx4ex0hY5fua2vMFx529ym5Yd0k6u6bQ+xxZFoA6t9TNGVUpENn+7xSE eQJRCRcx9dhmLmFi4kFdW/60oNy4wTMCB7r6mf51FbHl9UU0UTD1kwmmxj38abMRbwiL dlV++8dfTQAT6xJIe534bQK6P5bXgj9zUDXlluH0y8TM68KS1Ad7oReAJnNI5NQr5y5e jT/9dRoKzu5rMkdP73Yqfx1bmTBkDGGbrI2By3ccU+Bh3NxIUeQ11sz9V0SAIEd+RXEE dyPw== X-Gm-Message-State: AOAM5335+jIJtuT/wechmvIgJpFZYaWWd7tueH+v73srpln3/pvV35tS uvMYIE0kVGECE6FsWZ3qQGkTXP1y348XHL0jblC6XQ== X-Google-Smtp-Source: ABdhPJwIEHGAm7DzSP3xKm+77AEToECRuvrP8cgUmrbB0lzGVSUmywoXQzxjkzZXtHv9tY5NNIukY+sg0jyHYgnZ+oQ= X-Received: by 2002:a05:6512:a88:b0:473:e080:40e8 with SMTP id m8-20020a0565120a8800b00473e08040e8mr5030365lfu.359.1652486170889; Fri, 13 May 2022 16:56:10 -0700 (PDT) MIME-Version: 1.0 References: <20220504214437.2850685-1-zokeefe@google.com> <20220504214437.2850685-5-zokeefe@google.com> In-Reply-To: From: "Zach O'Keefe" Date: Fri, 13 May 2022 16:55:33 -0700 Message-ID: Subject: Re: [PATCH v5 04/13] mm/khugepaged: make hugepage allocation context-specific To: Yang Shi Cc: David Rientjes , Alex Shi , David Hildenbrand , Matthew Wilcox , Michal Hocko , Pasha Tatashin , Peter Xu , SeongJae Park , Song Liu , Vlastimil Babka , Zi Yan , Linux MM , Andrea Arcangeli , Andrew Morton , Arnd Bergmann , Axel Rasmussen , Chris Kennelly , Chris Zankel , Helge Deller , Hugh Dickins , Ivan Kokshaysky , "James E.J. Bottomley" , Jens Axboe , "Kirill A. Shutemov" , Matt Turner , Max Filippov , Miaohe Lin , Minchan Kim , Patrick Xia , Pavel Begunkov , Thomas Bogendoerfer Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 86135400C1 X-Stat-Signature: sfnw78y59i7a6kycfdp8yey4oy5yubbo X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Y0Tb3kJJ; spf=pass (imf04.hostedemail.com: domain of zokeefe@google.com designates 209.85.167.44 as permitted sender) smtp.mailfrom=zokeefe@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1652486161-890926 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 13, 2022 at 4:17 PM Yang Shi wrote: > > On Fri, May 13, 2022 at 4:05 PM Zach O'Keefe wrote: > > > > Thanks for the review, David! > > > > On Thu, May 12, 2022 at 1:02 PM David Rientjes wrote: > > > > > > On Wed, 4 May 2022, Zach O'Keefe wrote: > > > > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > > > index c94bc43dff3e..6095fcb3f07c 100644 > > > > --- a/mm/khugepaged.c > > > > +++ b/mm/khugepaged.c > > > > @@ -92,6 +92,10 @@ struct collapse_control { > > > > > > > > /* Last target selected in khugepaged_find_target_node() */ > > > > int last_target_node; > > > > + > > > > + struct page *hpage; > > > > + int (*alloc_charge_hpage)(struct mm_struct *mm, > > > > + struct collapse_control *cc); > > > > }; > > > > > > > > /** > > > > > > Embedding this function pointer into collapse_contol seems like it would > > > need some pretty strong rationale. Not to say that it should be a > > > non-starter, but I think the changelog needs to clearly indicate why this > > > is better/cleaner than embedding the needed info for a single allocation > > > and charge function to use. If the callbacks would truly be so different > > > that unifying them would be more complex, I think this makes sense. > > > > Mostly, this boils down to khugepaged having different a allocation > > pattern for NUMA/UMA ; the former scans the pages first to determine > > the right node, the latter preallocates before scanning. khugepaged > > has the luxury on UMA systems of just holding onto a hugepage > > indefinitely for the next collapse target. > > > > For MADV_COLLAPSE, we never preallocate, and so its pattern doesn't > > depend on NUMA or UMA configs. Trying to avoid "if (khugepaged) ... > > else" casing, defining this as a context-defined operation seemed > > appropriate. > > > > Collapsing both alloc and charging together was mostly a code > > cleanliness decision resulting from not wanting to embed a ->gfp() > > hook (gfp flags are used both by allocation and memcg charging). > > Alternatively, a .gfp member could exist - it would just need to be > > refreshed periodically in the khugepaged codepath. > > > > That all said - let me take another crack at seeing if I can make this > > work without the need for a function pointer here. > > I had a patch that removed UMA allocation, please refer to > https://lore.kernel.org/linux-mm/20210817202146.3218-1-shy828301@gmail.com/#t > > It was not made upstream due to some requests for further cleanup, but > unfortunately I haven't got time to look into it yet. > > If this page were merged, would that make your life easier? Hey Yang, First, sorry for missing that patch in the first place. I actually have some patches queued up that do a similar cleanup of khugepaged_prealloc_page() that was mentioned, but decided to not include them here. Second, removing the NUMA/UMA story does make this patch easier, I think (esp since the sched change was dropped for now). This is something I wanted while writing this series, but without the larger context referenced in your patch (most users don't build NUMA=n even on single node systems, and the pcp hugepage lists optimization) couldn't justify myself. Best, Zach