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 24950C35FFA for ; Wed, 19 Mar 2025 10:20:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3A6E1280002; Wed, 19 Mar 2025 06:20:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 32FC9280001; Wed, 19 Mar 2025 06:20:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1850D280002; Wed, 19 Mar 2025 06:20:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id F082E280001 for ; Wed, 19 Mar 2025 06:20:30 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 8A3A4ACF38 for ; Wed, 19 Mar 2025 10:20:32 +0000 (UTC) X-FDA: 83237906304.13.AAF78C1 Received: from mail-wm1-f67.google.com (mail-wm1-f67.google.com [209.85.128.67]) by imf01.hostedemail.com (Postfix) with ESMTP id 7EC784000E for ; Wed, 19 Mar 2025 10:20:30 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=Cb5Sj8vN; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf01.hostedemail.com: domain of mkoutny@suse.com designates 209.85.128.67 as permitted sender) smtp.mailfrom=mkoutny@suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742379630; a=rsa-sha256; cv=none; b=HaaoDLP6g4pfybsVN+PjJ3u24hdcTyZN6bHE64fuSkaZh41PBM6m2DM99uu2xjsMOfXZic mx/bsFsMlyji0c0ryXSDw1XfDpJdJFdbekWPadwtcc9TWST4fMhYc5WFXGxEBQcbonu/0w qtJm+umZ2zvjTrNWUf9FNySnhc8F+MI= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=Cb5Sj8vN; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf01.hostedemail.com: domain of mkoutny@suse.com designates 209.85.128.67 as permitted sender) smtp.mailfrom=mkoutny@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742379630; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uRvazjyez6/I61YAL9k58Mn3QJZtFdatNwV/fP1ktrc=; b=mVK4/iORpCjFxSfPDcWNdmNxsb+VyEtWbzxB+gzT1gKlJmRqOFjCSqYwlJ6ZHFZoweCufE y3kBsj5Tx4AYVh0gEMeLmhFMvx7N/iHtY9kXTbyM4bfRm/RBEm10h+u4hehMJk/Nzqb0oA /iFHKaV0b6TsWHGK17sZzNiI0WUp1eo= Received: by mail-wm1-f67.google.com with SMTP id 5b1f17b1804b1-43cfdc2c8c9so25680755e9.2 for ; Wed, 19 Mar 2025 03:20:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1742379629; x=1742984429; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=uRvazjyez6/I61YAL9k58Mn3QJZtFdatNwV/fP1ktrc=; b=Cb5Sj8vNAEDBX/7GdeSRSFTznB+/RcdRvcO9PCUhNLS/xYpAzk+mHVO7gNGVtlQdJc MaVgfcoJxO3+x++pkD2X5Imk9MnwxV+J0azCvcidzLWFU5Zp2aQi7yRRPKZQzfDhm0C4 beMITYTkhHbkRtjRQwaXW7NOwJhpektyBxj7DSepjReVRbwrRk9ROHjLK5hiNsa3bNCJ cFOZpqt7OKX8UW6b41t2hwlY0RQ0YbsquMSAqoL2+jegay86To2TvHmHwwZTfRBQGO0P oLk7FYtctjvrx4ZemYGh45hi+NEnKkgHYqUZkWCYSjbRZJRpSmOOqZuOq5OKAj/jumo7 peLA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742379629; x=1742984429; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=uRvazjyez6/I61YAL9k58Mn3QJZtFdatNwV/fP1ktrc=; b=KSMSTaRXWA+4PRq1/UCiJvevCI5vkfi4UEm6kzSqDRaZkqzNctHZodiauZDo+E5dQw Vz9FyUciSpqVcdaws3DWssSTZ7bLjuUrjpIC8wPbggP66UwVHzAlXkkddDoCFbHppBpm XYGZgpFtFNJ2vkC7D02w5jA3R2xd8hhm0TPSY05KY4F5R1rHzpzu4JifZf1LxS2d1BUb IkJVlNPnFkndUavDP/E4FXcdzQ3prIxJfro+/eWu/JzQMmoNlNYmVg5WV09AdZ2N7ge3 bQfXYYVkVk/CItvoumm/+s4gE+N2iCYJUCZao83oBah0b5MMnZ6xeW2Aox2krQmsXL5P Bwvg== X-Forwarded-Encrypted: i=1; AJvYcCXtkPytYWLC2kBufr4Rrno1jitz8LhbSMvJ5oYAoEPVAMIj5Qg6uXFF4qXhNxrzMVyM5mDvPu2+KA==@kvack.org X-Gm-Message-State: AOJu0YwIQTHfnvoCHwEI+T18VA45/l5E2tEKloG1tqb8SntO5LMASIRv fJQiz8mb6pG93KEL9FEldULwl3gsJDZUTubjmvptVRf4gjo7vA4ZsiPy4U0WaqE= X-Gm-Gg: ASbGncuokeGFxbHRObuOKUu3VjBg27kzUeG+V3qYTQ5G3V+KYK0g5/n1T9OH9Klvh2N Jd1TQ/a9AnrRz0JqUfKUMXuOJ5iMyYz/UIGf2yZLS4MvHZGG1uyW89s36kDJilGkEARySBNqF2N 09s9s+dn2sblnEMWuLNAZ8J61t0oE7myyuNt2uXe12An/42ixkWCMZwVQjwD/Fw+62D4xEVKyXj 0BOEdhng8n1fd1rAGjRkFmSfCliJ2C4VPPcQnpblno7RMlz2htvKM7+0oSFnsF7M+FgbE3DPpPI Z/9z3tMHNDOx4vjAvvC2jQ40zwt6oeBw3csLu0zbrq0CVmU= X-Google-Smtp-Source: AGHT+IFBijxngWJfWSrP0zxUR6KISoDK4M2HLz3EcfSwARMIp08CatCGZSMDqGgpT9PyUr4yPKbGrA== X-Received: by 2002:a05:600c:35cd:b0:43c:ec28:d301 with SMTP id 5b1f17b1804b1-43d4388dafamr10717475e9.26.1742379628671; Wed, 19 Mar 2025 03:20:28 -0700 (PDT) Received: from blackdock.suse.cz ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43d440ed4b8sm14200965e9.35.2025.03.19.03.20.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Mar 2025 03:20:28 -0700 (PDT) Date: Wed, 19 Mar 2025 11:20:26 +0100 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Greg Thelen Cc: Tejun Heo , Johannes Weiner , Andrew Morton , Yosry Ahmed , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Eric Dumazet Subject: Re: [PATCH] cgroup/rstat: avoid disabling irqs for O(num_cpu) Message-ID: References: <20250319071330.898763-1-gthelen@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="weublld6gas2cn5l" Content-Disposition: inline In-Reply-To: <20250319071330.898763-1-gthelen@google.com> X-Stat-Signature: e9qwqz8xtdfx3jjpfp4nh8wzdcfx5iha X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7EC784000E X-Rspam-User: X-HE-Tag: 1742379630-251988 X-HE-Meta: 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 nb3pPCnU 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 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: List-Subscribe: List-Unsubscribe: --weublld6gas2cn5l Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH] cgroup/rstat: avoid disabling irqs for O(num_cpu) MIME-Version: 1.0 Hello. On Wed, Mar 19, 2025 at 12:13:30AM -0700, Greg Thelen = wrote: > cgroup_rstat_flush_locked() grabs the irq safe cgroup_rstat_lock while > iterating all possible cpus. It only drops the lock if there is > scheduler or spin lock contention. If neither, then interrupts can be > disabled for a long time. On large machines this can disable interrupts > for a long enough time to drop network packets. On 400+ CPU machines > I've seen interrupt disabled for over 40 msec. This is peanuts, watchdog_thresh defaults to 10000 msec. (Tongue-in-cheek, to put that threshold into relation but I see the problem.) > The mode of memory.stat access latency after grouping by of 2 buckets: power > - without memory hogs: 64 usec =3D> 16 usec > - with memory hogs: 64 usec =3D> 8 usec > The memory.stat latency improves. >=20 > Signed-off-by: Eric Dumazet > Signed-off-by: Greg Thelen > Tested-by: Greg Thelen > --- > kernel/cgroup/rstat.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) FTR, the lock may end up split per-subsys [1] but this would still make sense for memcg's one. (I wonder if Tejun would consider it small enough then to avoid interrupt disabling. Then this could be converted to more widely used cond_resched_lock().) [1] https://lore.kernel.org/r/20250227215543.49928-4-inwardvessel@gmail.com/ But all in all, thanks for this and Acked-by: Michal Koutn=FD --weublld6gas2cn5l Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTd6mfF2PbEZnpdoAkt3Wney77BSQUCZ9qaaAAKCRAt3Wney77B SeofAQCRBDvo/r6sHgvgLjU9LafT+QwyWR/yByxGtg27ZjHPYwEAu/8pNOj+gJs7 sHE/DC6ID2Jh43yFSkVu8Y00gr+HxQg= =qq/w -----END PGP SIGNATURE----- --weublld6gas2cn5l--