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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C0C05CDB476 for ; Mon, 22 Jun 2026 18:56:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 34B766B00A8; Mon, 22 Jun 2026 14:52:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2883E6B00A9; Mon, 22 Jun 2026 14:52:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 14F246B00AA; Mon, 22 Jun 2026 14:52:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DEF236B00A8 for ; Mon, 22 Jun 2026 14:52:02 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id BCDA516549E for ; Mon, 22 Jun 2026 18:51:56 +0000 (UTC) X-FDA: 84908443032.29.05EC536 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) by imf15.hostedemail.com (Postfix) with ESMTP id 81C2CA0002 for ; Mon, 22 Jun 2026 18:51:53 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LQ5UmGuH; spf=pass (imf15.hostedemail.com: domain of jp.kobryn@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=jp.kobryn@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782154315; b=U6lr1ddbRAucrg1NmDOvADqjCNIkrkFRbi2BPLkX3XrEPQ0kuS9/xlO6rI/cGjqTs+OsWs 09PwsKZvJMI+63ZaUuv6WqZHFxHxB4WDb0m7hol9NgoiuMjAMRj5Tz2mfM4st+7/Dkx8s1 QguXk/Ft/mnLepdbEvzuL/lIAOAOSQE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782154315; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=P2FntB3QrBOJu+PV6zq+MqWBctOWxjgmfPOSEN+T8fQ=; b=rffo6t2fMi1H82arlHOcIbP1kjmGg4/fpb+wrL98zmgLdDuDwb1+Hh2mAJmKal0izCz1yf OXJV5YMV51cW0aCDF9jkoEvIYP0pKYYtj5JmNkDVH4iaDmayeuSLPr4aLRjLbe8RM58bsl vBFHhqbnMRpiuiCvGIRd+m6pp0lH+GY= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LQ5UmGuH; spf=pass (imf15.hostedemail.com: domain of jp.kobryn@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=jp.kobryn@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782154311; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=P2FntB3QrBOJu+PV6zq+MqWBctOWxjgmfPOSEN+T8fQ=; b=LQ5UmGuHzFWHqd4GHfy0JN96cJGwdY/deLgob6tnNEhffHniusw8d7dZWRP4O+D7ueXhqo saP0kl8mWM9szfoXk82w7rja1AKDf7JQnoge7BEACXrcmH6IDhOC6XNsL11Sh7ipaYm+9p Qo+lpUJuO2M0jG8xOjGMd2NExehc6rI= From: JP Kobryn To: linux-mm@kvack.org, willy@infradead.org, shakeel.butt@linux.dev, 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 Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v5] mm/lruvec: trace LRU add drains and drain-all requests Date: Mon, 22 Jun 2026 11:51:27 -0700 Message-ID: <20260622185127.24579-1-jp.kobryn@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 81C2CA0002 X-Stat-Signature: smexqr7md73hynquxpkkh6bqo6fq69o4 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782154313-554182 X-HE-Meta: U2FsdGVkX19fJ0JzHogQFOp2xZorXnV3xtZKSSrWad+rtcba0U9XWuZdIcQ5HHZucU3uSiaqV3IVPOli3wI2vOaQ1Jg1D8CcSqdMoRa6crWpfXk3P6suxpfnNj0MirP0sOWva3UQRqujHBxGjEHRFsWzJkGomkmC+kAQn62FzKs5WoAii4M/zFzTiUdAGrYT4WqS4fZDJd8ujc07HAFa1T48rjKIXa4ngxw16SQy5qzpxdy5EWzoNpmMcZmYO7nkFcdjG8VP0iv2za8SOua397PZ3YJoRQp/C95Tj9qX1O5OmybOU4j903RZXOEq54oV+ifJKH5kvTLrdonuUGnlnGQqXEzuapzauMcMaXwfKqik+k/urXIz59eRq9OwTPY+z0vJLizQ9MiLpqJlvRvQxLqV4fQ8WuW5oB+PYd1Ov8Fbjhyn+ep6JHfibCLrH5JDxr3VhOHg5rW/ya46OIW9V8IuRxsA0aRdoUosac8LHRzkfXlVFLT+aKL0S7+TsQiZFI5pOwo+3wA5cXPyxFJdNLhkdrk2iMvlHZjeyYmBQVAKg7CC+UuIrE/WzoBN5q2pxWErfC6KrZkzCLWHkfwoJCKboYFCCutx+83Mr6reBiuU0Z7Egnwg+O5HHrJ4OmMx66IAB4NMBscLCyEZaaog1EhN1ygD1KjTXjLsYMk0c8z87WepRdEdhM/YxG09BKWRrA0NbLcnoRvk7op2S93BmTo6UGliqztder74OdpQsq/jOODKOESVv9cBizgPA9P9lk1EM1eZ//oPAxTa1M20kDP7q2QqbNQO092grNA5g+Dl/CxGeWqVR79m9f6uVHHxFaHrcz0woOOa823kJShBv2EDBS1LmqUruGYQW78+TEnp/+Toly9ZFZyDJCPXwLu3cDjVkAZOo/uRzifkojTewumS1R6mD0ykC90gUOxvxmzEIdXFzXseouBO0dB5OEcqgxrHQAiz1cWm3vlEeSJ +ODIGtDE SiqDD3RteeIqhvbkSCKdS3cR3AqJWjO6+1Ptkvk/iaE26qSc1WbqYrVNXei6fSkNzUXX6mBGHlemrhYcQKfSKs1smUcGxWIUHwNI+KeE3qQm30s3tIZsZcV/Ie2BwTpOPYbLDYVYFnly3kSnwXHRHhAW68BKDncNSkVXAwcoBN8GI4a0k7g4joH/37LZAcscTKRHjMmdJs3OiePBW37ggIHXQFQXIWhFLjutW Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Note that DECLARE_TRACE() is used for these new trace hooks to avoid creating a new trace event ABI. Signed-off-by: JP Kobryn Reviewed-by: Barry Song Acked-by: Shakeel Butt --- v5: - change from trace events to bare trace hooks v4: https://lore.kernel.org/linux-mm/20260610234808.212397-1-jp.kobryn@linux.dev/ - renamed nr_folio_add to nr_folios in lru_add_drain() - renamed nr to nr_folios in tracepoint for consistency v3: https://lore.kernel.org/linux-mm/20260610195220.12403-1-jp.kobryn@linux.dev/ - restored and renamed tracepoint in __lru_add_drain_all v2: https://lore.kernel.org/linux-mm/20260609041156.31127-1-jp.kobryn@linux.dev/ - removed mm_lru_drain_all tracepoint v1: https://lore.kernel.org/linux-mm/20260609041156.31127-1-jp.kobryn@linux.dev/ include/trace/events/pagemap.h | 8 ++++++++ mm/swap.c | 7 ++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/include/trace/events/pagemap.h b/include/trace/events/pagemap.h index 171524d3526d..36c3a90f0acc 100644 --- a/include/trace/events/pagemap.h +++ b/include/trace/events/pagemap.h @@ -77,6 +77,14 @@ TRACE_EVENT(mm_lru_activate, TP_printk("folio=%p pfn=0x%lx", __entry->folio, __entry->pfn) ); +DECLARE_TRACE(mm_lru_add_drain, + TP_PROTO(int cpu, unsigned int nr_folios), + TP_ARGS(cpu, nr_folios)); + +DECLARE_TRACE(mm_lru_add_drain_all, + TP_PROTO(bool force_all_cpus), + TP_ARGS(force_all_cpus)); + #endif /* _TRACE_PAGEMAP_H */ /* This part must be outside protection */ diff --git a/mm/swap.c b/mm/swap.c index 588f50d8f1a8..460e56370b3c 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -694,9 +694,12 @@ void lru_add_drain_cpu(int cpu) { struct cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu); struct folio_batch *fbatch = &fbatches->lru_add; + unsigned int nr_folios = folio_batch_count(fbatch); - if (folio_batch_count(fbatch)) + if (nr_folios) { folio_batch_move_lru(fbatch, lru_add); + trace_mm_lru_add_drain_tp(cpu, nr_folios); + } fbatch = &fbatches->lru_move_tail; /* Disabling interrupts below acts as a compiler barrier. */ @@ -869,6 +872,8 @@ static inline void __lru_add_drain_all(bool force_all_cpus) if (WARN_ON(!mm_percpu_wq)) return; + trace_mm_lru_add_drain_all_tp(force_all_cpus); + /* * Guarantee folio_batch counter stores visible by this CPU * are visible to other CPUs before loading the current drain -- 2.54.0