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Mon, 22 Jan 2024 18:25:33 -0800 (PST) MIME-Version: 1.0 References: <20240121214413.833776-1-tjmercier@google.com> In-Reply-To: <20240121214413.833776-1-tjmercier@google.com> From: Yu Zhao Date: Mon, 22 Jan 2024 19:24:56 -0700 Message-ID: Subject: Re: [PATCH] Revert "mm:vmscan: fix inaccurate reclaim during proactive reclaim" To: "T.J. Mercier" Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , android-mm@google.com, yangyifei03@kuaishou.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 6767E18000B X-Stat-Signature: akfrgkstjpgggid5fshzeoupb5jz71gw X-HE-Tag: 1705976735-488407 X-HE-Meta: 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 HCNhW2gD MwnfKj6cAvP8W1SLHbH4F8Me/F3CbmGwTu/bBL5bt+N4CPgjtaMwupQOdZLoAdCB2Y+QQRH8JAq5n5ib9PSppTAM3cMFEDzPQcoi3quqy9kUbX8DqiTMEUVsu/Gb4ARKR20X7CvV/txRCGQjYbRt+Ypp/hrxqj13uKiX2qTiJwbrBgaPgdnQhRdIHVoUBNmy0Y6lH43Znmhm0ftGuENKPOsiWERMYP/CH9sWiX5uj0KoGwrk63cKCg4NFC9FqXtrvLgu9TSQ8QgwFl4fFyHnzADEs1bu3LLV23tYZMMvxcCzeciYlUBMbu6IQ0lSnwRvS4PGLyKAopmDXX8x4aoeBJhRmtzNuXqy/j+VHAvU5S6mZ/ZU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Jan 21, 2024 at 2:44=E2=80=AFPM T.J. Mercier = wrote: > > This reverts commit 0388536ac29104a478c79b3869541524caec28eb. > > Proactive reclaim on the root cgroup is 10x slower after this patch when > MGLRU is enabled, and completion times for proactive reclaim on much > smaller non-root cgroups take ~30% longer (with or without MGLRU). With > root reclaim before the patch, I observe average reclaim rates of > ~70k pages/sec before try_to_free_mem_cgroup_pages starts to fail and > the nr_retries counter starts to decrement, eventually ending the > proactive reclaim attempt. After the patch the reclaim rate is > consistently ~6.6k pages/sec due to the reduced nr_pages value causing > scan aborts as soon as SWAP_CLUSTER_MAX pages are reclaimed. The > proactive reclaim doesn't complete after several minutes because > try_to_free_mem_cgroup_pages is still capable of reclaiming pages in > tiny SWAP_CLUSTER_MAX page chunks and nr_retries is never decremented. > > The docs for memory.reclaim say, "the kernel can over or under reclaim > from the target cgroup" which this patch was trying to fix. Revert it > until a less costly solution is found. > > Signed-off-by: T.J. Mercier Fixes: 0388536ac291 ("mm:vmscan: fix inaccurate reclaim during proactive reclaim") Cc: