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Fri, 12 Sep 2025 17:35:32 +0800 Message-ID: <068a41eb-3a5c-4749-a8f6-c1bda1fb6a4b@linux.alibaba.com> Date: Fri, 12 Sep 2025 17:35:31 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 09/15] khugepaged: add per-order mTHP collapse failure statistics To: Nico Pache , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: david@redhat.com, ziy@nvidia.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kas@kernel.org, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com, richard.weiyang@gmail.com, lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org, jannh@google.com, pfalcato@suse.de References: <20250912032810.197475-1-npache@redhat.com> <20250912032810.197475-10-npache@redhat.com> From: Baolin Wang In-Reply-To: <20250912032810.197475-10-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B66F4C000A X-Rspamd-Server: rspam05 X-Stat-Signature: wmnpmz5h7motiugi3jo1t1ai3ao1hg4h X-Rspam-User: X-HE-Tag: 1757669737-123189 X-HE-Meta: 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 8DGjTjNc QeAtx87NLq6qStKM= 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 2025/9/12 11:28, Nico Pache wrote: > Add three new mTHP statistics to track collapse failures for different > orders when encountering swap PTEs, excessive none PTEs, and shared PTEs: > > - collapse_exceed_swap_pte: Increment when mTHP collapse fails due to swap > PTEs > > - collapse_exceed_none_pte: Counts when mTHP collapse fails due to > exceeding the none PTE threshold for the given order > > - collapse_exceed_shared_pte: Counts when mTHP collapse fails due to shared > PTEs > > These statistics complement the existing THP_SCAN_EXCEED_* events by > providing per-order granularity for mTHP collapse attempts. The stats are > exposed via sysfs under > `/sys/kernel/mm/transparent_hugepage/hugepages-*/stats/` for each > supported hugepage size. > > As we currently dont support collapsing mTHPs that contain a swap or > shared entry, those statistics keep track of how often we are > encountering failed mTHP collapses due to these restrictions. > > Signed-off-by: Nico Pache > --- LGTM. Reviewed-by: Baolin Wang