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 48AEECD8CB2 for ; Wed, 10 Jun 2026 00:29:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B4F5B6B00AB; Tue, 9 Jun 2026 20:29:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B26FE6B00AD; Tue, 9 Jun 2026 20:29:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A3CC36B00AE; Tue, 9 Jun 2026 20:29:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 93D3B6B00AB for ; Tue, 9 Jun 2026 20:29:44 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 420731C3161 for ; Wed, 10 Jun 2026 00:29:44 +0000 (UTC) X-FDA: 84862119888.08.277F0D6 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) by imf18.hostedemail.com (Postfix) with ESMTP id 483051C0008 for ; Wed, 10 Jun 2026 00:29:42 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=k2Ykltry; spf=pass (imf18.hostedemail.com: domain of jp.kobryn@linux.dev designates 91.218.175.174 as permitted sender) smtp.mailfrom=jp.kobryn@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781051382; 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=n6nRitLA5dXPldaPWFJdkV5WToaQRP9IZnc/9WgQeWE=; b=lX70zsx6HCEbSCJwyyMSmxS69qvYkCTGYRg6O8nvool5ta+gJFcSPqZ1jTXL8lno+6dweE 2TV34IaTFMNv7Cphhxt9vgWqML/Y543QupSodMPe+AkJN4b3QSwUzIzAkWcgJaHvASfmF2 HkMF2gOwzE5CV9xvCJwO5wGt5UnxEjg= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=k2Ykltry; spf=pass (imf18.hostedemail.com: domain of jp.kobryn@linux.dev designates 91.218.175.174 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=1781051382; b=ETOrXfrs6GVJlfDI+RQ8uOMyR2PNZqYZbjMUV1uICJRUnLMj6oZnCSS54EpEKGoDQGWjo2 dCGF9eJZDkZJu5AzA0S9vad8MmxYH4cvkeuvwu6ggbFZMAox4TMZfItSAKhTeSy6iCOiNb qjGuap50my7MQ/tT1Z/SUSoQKWANo+U= 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=1781051379; 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=n6nRitLA5dXPldaPWFJdkV5WToaQRP9IZnc/9WgQeWE=; b=k2YkltryaSxG3AYCOSdIpuXULa3fQ8OUMTERCHllVLhHajWA21GfAKY3mmj4y1OIY0Ll+u slAp1PHk4pDzgon8/6fFc2Z1xLfIvaOIPZ0bj/wjj8VBODn21z+8Aod9n4xk4kZzMLMlFT NhnyfLkdTaiG95Q8ZhTlOO10X6Mih8o= 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 v2] mm/lruvec: trace LRU add drains Date: Tue, 9 Jun 2026 17:29:19 -0700 Message-ID: <20260610002919.14102-1-jp.kobryn@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 483051C0008 X-Stat-Signature: fcin4fr4mfghtcdpz4bkd77sagfkj6fs X-Rspam-User: X-HE-Tag: 1781051382-742676 X-HE-Meta: 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 gFxUBrPd 5rqvAhAfVeAOpBi8gg96rDpyLl8uiOUQlh7Oucyx33+bykCuEm9MxrpLLhemDZZdaFSJEu48SiHz/cu4uaV61ZZ48RdEzdFk5j8Ot3if8xpK1ZVB5IXefbm3SQY/7NrCZQEU7gb1Iv3UgVHsq6D4DxSUEuLDZ4TMxjz5LQY1zvXJhEd9F4e7x1QMSTemkWBNqaMhqEXN81r2TFYw/X8kluU6iGqMGkjLvNQmF 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. Signed-off-by: JP Kobryn --- v2: - 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 | 19 +++++++++++++++++++ mm/swap.c | 5 ++++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/include/trace/events/pagemap.h b/include/trace/events/pagemap.h index 171524d3526d..fc28745507be 100644 --- a/include/trace/events/pagemap.h +++ b/include/trace/events/pagemap.h @@ -77,6 +77,25 @@ TRACE_EVENT(mm_lru_activate, TP_printk("folio=%p pfn=0x%lx", __entry->folio, __entry->pfn) ); +TRACE_EVENT(mm_lru_add_drain, + + TP_PROTO(int cpu, unsigned int nr), + + TP_ARGS(cpu, nr), + + TP_STRUCT__entry( + __field(int, cpu ) + __field(unsigned int, nr ) + ), + + TP_fast_assign( + __entry->cpu = cpu; + __entry->nr = nr; + ), + + TP_printk("cpu=%d nr=%u", __entry->cpu, __entry->nr) +); + #endif /* _TRACE_PAGEMAP_H */ /* This part must be outside protection */ diff --git a/mm/swap.c b/mm/swap.c index 588f50d8f1a8..8fd6808bfc6e 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_add = folio_batch_count(fbatch); - if (folio_batch_count(fbatch)) + if (nr_folios_add) { folio_batch_move_lru(fbatch, lru_add); + trace_mm_lru_add_drain(cpu, nr_folios_add); + } fbatch = &fbatches->lru_move_tail; /* Disabling interrupts below acts as a compiler barrier. */ -- 2.54.0