From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5A8833FE15 for ; Thu, 4 Dec 2025 12:42:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764852145; cv=none; b=TxRB7axiXI1n3CJcQC6/GVr2UkJIqcGJSVVdgD8M+6n1iSv0igC9A0GANeEL6WMuigbwr3w/VjwtA8DCzjNzMrm65Me6gMn1MQxO2tBJfPrBhV+GaXDmlyxPkA+4hZAQNscIYFNFllCgkwXjDxBPJ5CaN5Bs9pu8kKng0gFvIlE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764852145; c=relaxed/simple; bh=8IEFSuSrYHqIBmea/jkeB6Aa+5WiQ6kLiFusAPNBjhs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ey5KNrVOMx1hwlqXdAccsPFRmtc/nDiwUwhUhaPAwdndEqUQAzqp9EtW4fR5R4WHq4Hh8jArL6oupMGdIqfjUg0qCW2/Ugp3g2ee9lQ8BLqiRRyqVq/Mfr+tqcayDzaXfUOQwBcszA0Ml5AN38HPG/7dxRTM/cEPHFaPuMK3/R0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=brJP1+z2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="brJP1+z2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B35E5C4CEFB; Thu, 4 Dec 2025 12:42:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764852144; bh=8IEFSuSrYHqIBmea/jkeB6Aa+5WiQ6kLiFusAPNBjhs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=brJP1+z26wVKIZMVtWGv/VObdgbyW/nl5Ryl8E1JWdUv+s2XaZjH/yZxbMdIkpAE/ vExncNyidXnpQz5I4ou62AkWSsUcC5ChMDID0fXSk91IYIVfhwaE6Vp6viAt14EWYH fP0o1P1rhEZDV4eSUcYD0p5s0zT7Q/4IC8C761st0z7Ybc9HIszJuIjNvH04cCoCJp IfymBV1DwHyojOEaHlFGZ2inIDBlbqyv+KvnkQAbj5zCS2BQI2T3/sqwGUEEZkzgeV ceRTeF/+edGXHQP7zqyQ93mpQmtIidZwJWsH4RwraNfpz5vjq6F2k7+RnWvbaJBmmZ lR0n580s61n0g== Message-ID: <308c809e-160a-4829-a8b9-9c7682fcd251@kernel.org> Date: Thu, 4 Dec 2025 13:42:18 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -next v2] mm: vmscan: correct nr_requested tracing in scan_folios To: Chen Ridong , akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, yuzhao@google.com, jaewon31.kim@samsung.com, ioworker0@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com, chenridong@huawei.com References: <20251204122355.1822919-1-chenridong@huaweicloud.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251204122355.1822919-1-chenridong@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/4/25 13:23, Chen Ridong wrote: > From: Chen Ridong > > When enabling vmscan tracing, it is observed that nr_requested is always > 4096, which is confusing. > > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > > This is because it prints MAX_LRU_BATCH, which is meaningless as it's a > constant. To fix this, modify it to print capped valued. > > Fixes: 8c2214fc9a47 ("mm: multi-gen LRU: reuse some legacy trace events") > Signed-off-by: Chen Ridong > --- > mm/vmscan.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 584f41eb4c14..a0a74cac947b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4404,7 +4404,8 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, > int scanned = 0; > int isolated = 0; > int skipped = 0; > - int remaining = min(nr_to_scan, MAX_LRU_BATCH); > + int scan_batch = min(nr_to_scan, MAX_LRU_BATCH); > + int remaining = scan_batch; > struct lru_gen_folio *lrugen = &lruvec->lrugen; > struct mem_cgroup *memcg = lruvec_memcg(lruvec); > > @@ -4464,7 +4465,7 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, > count_memcg_events(memcg, item, isolated); > count_memcg_events(memcg, PGREFILL, sorted); > __count_vm_events(PGSCAN_ANON + type, isolated); > - trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, MAX_LRU_BATCH, > + trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, scan_batch, > scanned, skipped, isolated, > type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON); > if (type == LRU_GEN_FILE) Acked-by: David Hildenbrand (Red Hat) -- Cheers David