From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) (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 4695D19D89E for ; Mon, 9 Feb 2026 02:20:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770603658; cv=none; b=r8tgdOo07hly31f06uUFXDSE7TU/5WxVfxezHirz0B5W5zy+IJzQk+cGO1hT6f4jXoOPlffidvSPonS/hca6Eb6V7tJjMCwSSj+vNwyDYS5X9Dc2R2AL8JSbmLl/o/wNf8RAROkDMDa3iyVvIzj4iLxPSK2OkWDLDgTlJ8P4EeQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770603658; c=relaxed/simple; bh=36vmme40spUORRRGja9cLP0VDiz/9cWAynETdXfq024=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=B1/A+RH0mI2OchV8u5vWUhSZdaSqQeozTn9MiHCUTZ8wrQiBiI5UBGf5buW7GtaMZgHVpMCQyw+1kgrIJ/NjxkFk6dfiCM3fmLEP9NdmM2B2pTQtEE+ELNdtj5xa9b6Xp/kjKBxsRz3KXnySqPlat52NdjjYf1iX6F/AzHU9pks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=aLXexndb; arc=none smtp.client-ip=95.215.58.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="aLXexndb" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1770603655; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OQN407ZmYQBloA6BAF7c/l2mr9zhF3xU5Rg1TJMGq9I=; b=aLXexndbUwlN08ZbKLTgVZ3S+Cbm85Eh/H41U4JdL/Q+E/mWv4gQ9k3I628Wp/AiIU5+LQ laJ0F7j7YblXLM10Jh4ObSziGAKFyblkgQO3O1+S82HtB1jar0rYvFDzqOqUVeo8pp/46f VFtG+BLtbatP7AajwURsO3VFzaSFlbk= Date: Mon, 9 Feb 2026 10:20:42 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2 1/2] mm: zswap: add per-memcg stat for incompressible pages To: Jiayuan Chen , linux-mm@kvack.org Cc: Jiayuan Chen , Nhat Pham , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Jonathan Corbet , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Yosry Ahmed , Shuah Khan , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260206072220.144008-1-jiayuan.chen@linux.dev> <20260206072220.144008-2-jiayuan.chen@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <20260206072220.144008-2-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 2026/2/6 15:22, Jiayuan Chen wrote: > From: Jiayuan Chen > > The global zswap_stored_incompressible_pages counter was added in commit > dca4437a5861 ("mm/zswap: store to track how many pages are stored in raw (uncompressed) form in zswap. > However, in containerized environments, knowing which cgroup is > contributing incompressible pages is essential for effective resource > management [1]. > > Add a new memcg stat 'zswap_incomp' to track incompressible pages per > cgroup. This helps administrators and orchestrators to: > > 1. Identify workloads that produce incompressible data (e.g., encrypted > data, already-compressed media, random data) and may not benefit from > zswap. > > 2. Make informed decisions about workload placement - moving > incompressible workloads to nodes with larger swap backing devices > rather than relying on zswap. > > 3. Debug zswap efficiency issues at the cgroup level without needing to > correlate global stats with individual cgroups. > > While the compression ratio can be estimated from existing stats > (zswap / zswapped * PAGE_SIZE), this doesn't distinguish between > "uniformly poor compression" and "a few completely incompressible pages > mixed with highly compressible ones". The zswap_incomp stat provides > direct visibility into the latter case. > > [1]: https://lore.kernel.org/linux-mm/CAF8kJuONDFj4NAksaR4j_WyDbNwNGYLmTe-o76rqU17La=nkOw@mail.gmail.com/ > Acked-by: Nhat Pham > Signed-off-by: Jiayuan Chen Reviewed-by: Chengming Zhou Thanks! > --- > Documentation/admin-guide/cgroup-v2.rst | 5 +++++ > include/linux/memcontrol.h | 1 + > mm/memcontrol.c | 8 ++++++++ > 3 files changed, 14 insertions(+) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 7f5b59d95fce..78a329414615 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1737,6 +1737,11 @@ The following nested keys are defined. > zswpwb > Number of pages written from zswap to swap. > > + zswap_incomp > + Number of incompressible pages currently stored in zswap > + without compression. These pages could not be compressed to > + a size smaller than PAGE_SIZE, so they are stored as-is. > + > thp_fault_alloc (npn) > Number of transparent hugepages which were allocated to satisfy > a page fault. This counter is not present when CONFIG_TRANSPARENT_HUGEPAGE > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index b6c82c8f73e1..d8ec05dd5d43 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -39,6 +39,7 @@ enum memcg_stat_item { > MEMCG_KMEM, > MEMCG_ZSWAP_B, > MEMCG_ZSWAPPED, > + MEMCG_ZSWAP_INCOMP, > MEMCG_NR_STAT, > }; > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 007413a53b45..a6b6cf5f1aeb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -341,6 +341,7 @@ static const unsigned int memcg_stat_items[] = { > MEMCG_KMEM, > MEMCG_ZSWAP_B, > MEMCG_ZSWAPPED, > + MEMCG_ZSWAP_INCOMP, > }; > > #define NR_MEMCG_NODE_STAT_ITEMS ARRAY_SIZE(memcg_node_stat_items) > @@ -1346,6 +1347,7 @@ static const struct memory_stat memory_stats[] = { > #ifdef CONFIG_ZSWAP > { "zswap", MEMCG_ZSWAP_B }, > { "zswapped", MEMCG_ZSWAPPED }, > + { "zswap_incomp", MEMCG_ZSWAP_INCOMP }, > #endif > { "file_mapped", NR_FILE_MAPPED }, > { "file_dirty", NR_FILE_DIRTY }, > @@ -5458,6 +5460,9 @@ void obj_cgroup_charge_zswap(struct obj_cgroup *objcg, size_t size) > memcg = obj_cgroup_memcg(objcg); > mod_memcg_state(memcg, MEMCG_ZSWAP_B, size); > mod_memcg_state(memcg, MEMCG_ZSWAPPED, 1); > + /* size == PAGE_SIZE means compression failed, page is incompressible */ > + if (size == PAGE_SIZE) > + mod_memcg_state(memcg, MEMCG_ZSWAP_INCOMP, 1); > rcu_read_unlock(); > } > > @@ -5481,6 +5486,9 @@ void obj_cgroup_uncharge_zswap(struct obj_cgroup *objcg, size_t size) > memcg = obj_cgroup_memcg(objcg); > mod_memcg_state(memcg, MEMCG_ZSWAP_B, -size); > mod_memcg_state(memcg, MEMCG_ZSWAPPED, -1); > + /* size == PAGE_SIZE means compression failed, page is incompressible */ > + if (size == PAGE_SIZE) > + mod_memcg_state(memcg, MEMCG_ZSWAP_INCOMP, -1); > rcu_read_unlock(); > } >