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From: Shakeel Butt To: JP Kobryn Cc: linux-mm@kvack.org, willy@infradead.org, usama.arif@linux.dev, akpm@linux-foundation.org, vbabka@kernel.org, mhocko@suse.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, kasong@tencent.com, qi.zheng@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/lruvec: trace LRU add drains and drain-all requests Message-ID: References: <20260610195220.12403-1-jp.kobryn@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260610195220.12403-1-jp.kobryn@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 3EBD2A0002 X-Rspam-User: X-Stat-Signature: 1szgocm9sz5wzq7yhz1tsxxwnpb99ia7 X-Rspamd-Server: rspam08 X-HE-Tag: 1781126023-108592 X-HE-Meta: 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 qB1lfLwK RPdxjH1VkU5cNEquTF1OXslHSKbANJQ+sU6i2MoIB5gkjzTHAXwj0SbDvftuYrOV6pHCq0Fvoo8qbZBUaGgQlUfqhQrtwf7QnxUvvPy6kUYdau9ImOmMnDK6MpukIfR8k7moMlmnt911WMAd8TZ4rY90RS/OmFQMVBNmFTjtbSci7F4eeDvZa7fuSmswgwqEfYRmuJmNrM+ZFUQ5kaPKNc67+bA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 10, 2026 at 12:52:20PM -0700, JP Kobryn wrote: > LRU add batches can be drained before they reach capacity. This can be a > source of LRU lock contention, but it is not currently possible to > attribute these drains to callers with existing tracepoints. > > Add mm_lru_add_drain to report the CPU and lru_add batch count when an > lru_add batch is drained. This allows tracing to distinguish full drains > from partial drains and attribute them to the calling stack. > > Add mm_lru_add_drain_all to capture callers of __lru_add_drain_all and > whether they set the force flag for all CPUs. The tracepoint resembles > the signature of the enclosing function, but is needed because of > potential inlining. > > Signed-off-by: JP Kobryn Acked-by: Shakeel Butt