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b=W7bVQuu1YhAGqRyw7SMcvmMCv40e3ociO+Czj8+dNoHVab7xNQmZEaZ7ZehXOSsW8uYKsuf6i6ABNE0Es7GS1qw1LWje4hAvVaxCf6vRMR5iYHF9B5Z5GaO2HCWImsGLBD/Gss77KDMlGqi2X2DO2taZ58NPIoa2DPYiY9wd/jg= Received: from 30.74.144.130(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wud5Ubw_1765518513 cluster:ay36) by smtp.aliyun-inc.com; Fri, 12 Dec 2025 13:48:33 +0800 Message-ID: <7f681d9d-0b24-4230-bd5a-bf056c6c396e@linux.alibaba.com> Date: Fri, 12 Dec 2025 13:48:32 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm/shmem: add mTHP swpout fallback statistics in shmem_writeout() To: Weilin Tong , Hugh Dickins Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20251212031250.206571-2-tongweilin@linux.alibaba.com> From: Baolin Wang In-Reply-To: <20251212031250.206571-2-tongweilin@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B0DC21C001D X-Stat-Signature: nsmmffrhny4omqtwh3yzod39ofm3jpaw X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1765518517-972963 X-HE-Meta: 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 jn4C43GG 4VAWyATUlsNO5PLL67ZGxV/9KbcFywtlQeykUcL4mF6FlQ8dCW3kSTefCvCEN3tHGSvJxI4D6peTsmV76NgSdOD4MhF3rMiixdb6TbA8exK1L4ulC34umfnn+q/Cvm5R6TVZHMPHAjAcyndteFN0/sjQKNmYy0tgrvHQ/8Cr7mwE0exaVo68AAeZpSpvgYFAk1n6y7F6oo98/RS6GFZKMMFza4yhRlD+IU8+RM0rKaEZLeDV+l7FuNWneSAtGyCmMWikitlI9QD9LKD81Euxkjk92HYajPPaP4pTajg2d5GRzkgoabfS8UJU9nnkMKfYc7ymYJOy4VlNx2ewnkfjR0/NJ6voRIKxyNy5tX9bdYdimwrJ+lcn+G+uc1g== 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: On 2025/12/12 11:12, Weilin Tong wrote: > Currently, when shmem mTHPs are split and swapped out via shmem_writeout(), > there are no unified statistics to trace these mTHP swpout fallback events. > This makes it difficult to analyze the prevalence of mTHP splitting and > fallback during swap operations, which is important for memory diagnostics. > > Here we add statistics counting for mTHP fallback to small pages > when splitting and swapping out in shmem_writeout(). > > Signed-off-by: Weilin Tong > --- Looks reasonable to me. Thanks. Reviewed-by: Baolin Wang > mm/shmem.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 3f194c9842a8..aa624c447358 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1593,11 +1593,23 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug, > } > > if (split) { > + int order; > + > try_split: > + order = folio_order(folio); > /* Ensure the subpages are still dirty */ > folio_test_set_dirty(folio); > if (split_folio_to_list(folio, folio_list)) > goto redirty; > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + if (order >= HPAGE_PMD_ORDER) { > + count_memcg_folio_events(folio, THP_SWPOUT_FALLBACK, 1); > + count_vm_event(THP_SWPOUT_FALLBACK); > + } > +#endif > + count_mthp_stat(order, MTHP_STAT_SWPOUT_FALLBACK); > + > folio_clear_dirty(folio); > } >