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 ADADCC433FE for ; Wed, 16 Mar 2022 00:02:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 36F398D0002; Tue, 15 Mar 2022 20:02:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 31E988D0001; Tue, 15 Mar 2022 20:02:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1BF798D0002; Tue, 15 Mar 2022 20:02:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0185.hostedemail.com [216.40.44.185]) by kanga.kvack.org (Postfix) with ESMTP id 09D7B8D0001 for ; Tue, 15 Mar 2022 20:02:30 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A7CFCA0F92 for ; Wed, 16 Mar 2022 00:02:29 +0000 (UTC) X-FDA: 79248297618.31.9189011 Received: from mail-ej1-f54.google.com (mail-ej1-f54.google.com [209.85.218.54]) by imf03.hostedemail.com (Postfix) with ESMTP id 55F1420008 for ; Wed, 16 Mar 2022 00:02:29 +0000 (UTC) Received: by mail-ej1-f54.google.com with SMTP id yy13so948778ejb.2 for ; Tue, 15 Mar 2022 17:02:29 -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=0ZUG3daTjBSNeQ09LqP7cMF4OOdcfPX1L9Gvauwm3p4=; b=cNgJESNNXO6CVxh1c4d+IFacASUh8b8hgVKzMhf0/q+zag5BY3uZQIOsYYfoyq5v8o IhePtWh0pGptQ8qaIWEZ9Z/zv09alp3AXeFV1V4XZ2OoY8X6MAwlF5HKMjpar3uNPtFm ygSfHnZ8QD0cB6Yj7WRQ3IHzNH/l3OyZSY/3fCDCpwVIfWYy/6jA4VassSG4GsJUrTwo zXqIviTwFJiQf8MjjTwCtIREDtGBO5h4bt40DxwnQmmDI9mV99EdLYSG+eHM4Cv3gicF ZYzHFnrWPAIcDyFPZvWnIybAMgGlcum3r7hvW6j9MY0MFkON9H2SBXz5gtlzGLYN0KbE uGBA== 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=0ZUG3daTjBSNeQ09LqP7cMF4OOdcfPX1L9Gvauwm3p4=; b=N6W2x+hgVw0n3HXb8Q8hj1Axo2Hlp8Jc0fT1FfeUl7t2HDB73IAKkee5DdlaStxlNz EUTFIGdQnCrIbKtevANFzSXAq2mTDXPgqvslhQcwYXvblOVhElsdpYlC/9e1igWLQrVy WJQ910b5iy16/M5iRAZHC0GUyaBelRZbLhpuZ5XhQcFKnbQ3mA9o2bqpZvuntJGuT0GQ F5phtk0PkLfK3VUCSbHGzAxGppQkGaxVdm+2GNdckmkaq+iCswYUTdj+cB0f/QNgk1p9 mgeATGsdkQ/cEDrMbChxEa7c5bpflq2zExAWEmQajTmTmHW+VJdPVdvMsbgUptyRQM9K r17Q== X-Gm-Message-State: AOAM530mq+XNKWSJZh0wNmQaex6HswVfAiVltB2AQz29O3Rr1Af4BlDl t+IeRF5hY2W54sX4k4nNv9NRFrHG+R9J43j8m3EnpA== X-Google-Smtp-Source: ABdhPJwOS0I4hArhmI83705iboyKEE6Janp7V5RBBNVLVBJ2XiVer4+vbsGzg4VWhvkr9vEvKQ8DOpavrHz0PqdnhEM= X-Received: by 2002:a17:907:8692:b0:6da:866c:6355 with SMTP id qa18-20020a170907869200b006da866c6355mr25354574ejc.174.1647388947747; Tue, 15 Mar 2022 17:02:27 -0700 (PDT) MIME-Version: 1.0 References: <20220315172221.9522-1-bgeffon@google.com> In-Reply-To: From: Brian Geffon Date: Tue, 15 Mar 2022 20:01:51 -0400 Message-ID: Subject: Re: [PATCH] zram: Add a huge_idle writeback mode To: Matthew Wilcox Cc: Andrew Morton , Minchan Kim , Nitin Gupta , Sergey Senozhatsky , LKML , linux-doc@vger.kernel.org, linux-block@vger.kernel.org, linux-mm Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 55F1420008 X-Stat-Signature: widh5kmzxgmgjd1brrmtzbmmi7soy3pq X-Rspam-User: Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=cNgJESNN; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf03.hostedemail.com: domain of bgeffon@google.com designates 209.85.218.54 as permitted sender) smtp.mailfrom=bgeffon@google.com X-Rspamd-Server: rspam02 X-HE-Tag: 1647388949-960418 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 Tue, Mar 15, 2022 at 1:44 PM Matthew Wilcox wrote: > > On Tue, Mar 15, 2022 at 01:34:21PM -0400, Brian Geffon wrote: > > On Tue, Mar 15, 2022 at 1:28 PM Matthew Wilcox wrote: > > > > > > On Tue, Mar 15, 2022 at 10:22:21AM -0700, Brian Geffon wrote: > > > > Today it's only possible to write back as a page, idle, or huge. > > > > A user might want to writeback pages which are huge and idle first > > > > as these idle pages do not require decompression and make a good > > > > first pass for writeback. > > > > > > We're moving towards having many different sizes of page in play, > > > not just PMD and PTE sizes. Is this patch actually a good idea in > > > a case where we have, eg, a 32kB anonymous page on a system with 4kB > > > pages? How should zram handle this case? What's our cut-off for > > > declaring a page to be "huge"? > > > > > > > Huge isn't a great term IMO, but it is what it is. ZRAM_HUGE is used > > to identify pages which are incompressible. Since zram is a block > > device which presents PAGE_SIZED blocks, do these new changes which > > involve many different page sizes matter as that seems orthogonal to > > the block subsystem. Correct me if I'm misunderstanding. > > Oh, so ZRAM's concept of huge is not the same as the "huge" in > "hugetlbfs" or "THP"? That's not at all confusing ... I do not disagree, but there isn't much that can be done about it at this point given the sysfs file takes an argument called "huge"