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 39E9BC46CD3 for ; Sun, 24 Dec 2023 17:18:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C6D6E6B0074; Sun, 24 Dec 2023 12:18:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C1D0B6B0075; Sun, 24 Dec 2023 12:18:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE4C96B0078; Sun, 24 Dec 2023 12:18:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id A0DD16B0074 for ; Sun, 24 Dec 2023 12:18:08 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 7666914037E for ; Sun, 24 Dec 2023 17:18:08 +0000 (UTC) X-FDA: 81602369856.28.C9C7A66 Received: from mail-pg1-f177.google.com (mail-pg1-f177.google.com [209.85.215.177]) by imf30.hostedemail.com (Postfix) with ESMTP id 9ACDF8001A for ; Sun, 24 Dec 2023 17:18:06 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=YA6DDAQR; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf30.hostedemail.com: domain of chriscli@google.com designates 209.85.215.177 as permitted sender) smtp.mailfrom=chriscli@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1703438286; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=3hFLSnZfOPa4HbeCcp8WZcEpXNOy9FTVGa6+3rCmbwU=; b=SbdRRoB71bVgqGVCJgr+U6A5VabxLOTRRUCoAG+LPayXzHICBJDF9Hft3kMqs7+apu7Sbn GeIHEgvuhCV3ixbrufshImfu5zmHqLqf0fnw5XMrtxnw3fZ0cGyHQwGvsLF6thLdRA1mIo Jsddsw6i96ZX/31OYYAKDGTw6Ms8rWs= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=YA6DDAQR; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf30.hostedemail.com: domain of chriscli@google.com designates 209.85.215.177 as permitted sender) smtp.mailfrom=chriscli@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1703438286; a=rsa-sha256; cv=none; b=M9G0algSb/GxESRXSEW+XFtUHUEWAtUqQzFdgVn4GNGuq0bAul+LLZ7YLjnnYmBWofZRC3 zOdXbmQpAW6uAjw67CQ0Ql+P9EX51UEUJTUHT1F5dOmq+JzovHbfP/SDiX//nNSl/Q1ZAP KHLylIt5t+Jcpi1g2t3Hki8L7uikN7Y= Received: by mail-pg1-f177.google.com with SMTP id 41be03b00d2f7-5bdbe2de25fso2619469a12.3 for ; Sun, 24 Dec 2023 09:18:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1703438285; x=1704043085; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=3hFLSnZfOPa4HbeCcp8WZcEpXNOy9FTVGa6+3rCmbwU=; b=YA6DDAQRMO8+BekOWnoE6kk2KRxES8SlDyKmceijx5bAq0Mc+Hx157RE3BHQm0ul8J OYqzoJLZZLsdPuqSdvDe2ZE6hzRhKq7EtzUT3unYyA3Lz/LyCL72QTFp4OFLlmnxlrjY hZ3kgHSUCyw0N1vcXv0pSEZRYxOAlN5Bee9j76RAfdtx0+q0O4eD6rD2J7xUikn9o/6A tvhEAv2LODXTBRATxL138NLWDWP32no2dlUWyrl2ozNbS698ro7+zu3rXcoQv4vmbSaI T5Pu+mOiY0dZ7tTw5X00pPp4s2x2Qt6qxJArOCr4736s8NeXWaKx9IYfKR8Eyyt2cayB NrhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703438285; x=1704043085; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3hFLSnZfOPa4HbeCcp8WZcEpXNOy9FTVGa6+3rCmbwU=; b=KUsfIXv1qkH4PDXkkcsUJZviEFhyYemcE/NLR3ksWDTZ4dkLQIMsvetgcnLT3bCmOc S9ElBxaevBCmy61QKmLVYmA6wZnR+1VSKaVQSiKg4IKcHrjkcDNuzLYNTJHgPns4H29L 5Ay0gdL2CYOlkst474TLziJVMkA53NuAz/o40HZ5OdVBJtR4CCdXRPgj4wqr89z2GGCT bFvYTXi1PfSyy70yDuoAhIL+zI44QBb/CK1kyyd99Q2lb+Yzu/Z/cEJgLwr/5E32jFZJ ygoAFJomWxjAIDBaNkdkilYryDUKlFnnWpfo6/c/hNkr5ZWlpIe73S6xQtG4GLSiIvrs Zhhg== X-Gm-Message-State: AOJu0Ywop8deduDhp4yMEf872D7vnWxSQfNxZqD7ENBrI12pecAPlehM fcwDio7/smUKvQr1P0cG4C3K9hQwLTbPXjjr17qvhgvFkFOV X-Google-Smtp-Source: AGHT+IHqdGi+qJAhaciG+1KGIMfLpbW26gbSL9yRw9d1ad7j+3u5CPf+ZOWnMczughCoPqVc0v+t9WY5gzRQbV6uAJg= X-Received: by 2002:a17:902:eb83:b0:1d3:efef:d84b with SMTP id q3-20020a170902eb8300b001d3efefd84bmr5625964plg.70.1703438285308; Sun, 24 Dec 2023 09:18:05 -0800 (PST) MIME-Version: 1.0 References: <20231207192406.3809579-1-nphamcs@gmail.com> <20231221005725.3446672-1-nphamcs@gmail.com> In-Reply-To: <20231221005725.3446672-1-nphamcs@gmail.com> From: Chris Li Date: Sun, 24 Dec 2023 09:17:54 -0800 Message-ID: Subject: Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling (fix) To: Nhat Pham Cc: akpm@linux-foundation.org, tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, cerasuolodomenico@gmail.com, yosryahmed@google.com, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, hughd@google.com, corbet@lwn.net, konrad.wilk@oracle.com, senozhatsky@chromium.org, rppt@kernel.org, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, david@ixit.cz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 9ACDF8001A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: an1snrf3dshzezntmdeb3jb1hgegiasq X-HE-Tag: 1703438286-611311 X-HE-Meta: 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 UKV9Zg9Q AxSrNB418hkQ1Iq3CDzDann+73j8xwPyhgbBEcQBZPmRu2k5eJ521jNlT0Pv18IDD4ROOiry3VPZdbOhhGRhJIsN71kHsiVmSC0aXlnavhtBBXjs10lOjm7xW4kQ6MBH9Q85bIzDpj9UqM6yvSSzshfPTelOzRqX5p/CM47qf9tlWp3GcVlzoTgIltjIpSJor+a2Kd4pJrak6vp+l2FNJtVF2qAwlS6+FjxqFe1ra8vr1vTQ4T77qmdoj/yNczMcEBZ5pgeEvCPt45Xe9e6HEq/NpAHlYgh0uWjSBlntSwJZoUqrrnynyiNmX9fzfWYLh52iTPzr2uiBBx18= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000049, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Nhat, Acked-by: Chris Li I think a follow up step would be having some patches to address it rather than document it that oh yes, we have a problem in that situation. Chris On Wed, Dec 20, 2023 at 4:57=E2=80=AFPM Nhat Pham wrote= : > > Add a caveat about recurring zswap store failures leading to reclaim > inefficiency. > > Suggested-by: Yosry Ahmed > Signed-off-by: Nhat Pham > --- > Documentation/admin-guide/cgroup-v2.rst | 5 ++++- > Documentation/admin-guide/mm/zswap.rst | 4 ++++ > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admi= n-guide/cgroup-v2.rst > index 2b4ac43efdc8..5ec7dd753cd1 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1686,7 +1686,10 @@ PAGE_SIZE multiple when read back. > > When this is set to 0, all swapping attempts to swapping devices > are disabled. This included both zswap writebacks, and swapping d= ue > - to zswap store failure. > + to zswap store failures. If the zswap store failures are recurrin= g > + (for e.g if the pages are incompressible), users can observe > + reclaim inefficiency after disabling writeback (because the same > + pages might be rejected again and again). > > Note that this is subtly different from setting memory.swap.max t= o > 0, as it still allows for pages to be written to the zswap pool. > diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin= -guide/mm/zswap.rst > index cfa653130346..b42132969e31 100644 > --- a/Documentation/admin-guide/mm/zswap.rst > +++ b/Documentation/admin-guide/mm/zswap.rst > @@ -159,6 +159,10 @@ zswap itself) on a cgroup-basis as follows: > > echo 0 > /sys/fs/cgroup//memory.zswap.writeback > > +Note that if the store failures are recurring (for e.g if the pages are > +incompressible), users can observe reclaim inefficiency after disabling > +writeback (because the same pages might be rejected again and again). > + > When there is a sizable amount of cold memory residing in the zswap pool= , it > can be advantageous to proactively write these cold pages to swap and re= claim > the memory for other use cases. By default, the zswap shrinker is disabl= ed. > -- > 2.34.1 >