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Wed, 22 Jul 2026 19:27:12 -0700 (PDT) Date: Wed, 22 Jul 2026 22:27:08 -0400 From: Johannes Weiner To: Hao Jia Cc: akpm@linux-foundation.org, tj@kernel.org, shakeel.butt@linux.dev, mhocko@kernel.org, yosry@kernel.org, mkoutny@suse.com, nphamcs@gmail.com, chengming.zhou@linux.dev, muchun.song@linux.dev, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Hao Jia Subject: Re: [PATCH v2 2/2] mm/zswap: Support batch writeback in shrink_memcg() Message-ID: References: <20260717085151.22822-1-jiahao.kernel@gmail.com> <20260717085151.22822-3-jiahao.kernel@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260717085151.22822-3-jiahao.kernel@gmail.com> On Fri, Jul 17, 2026 at 04:51:51PM +0800, Hao Jia wrote: > @@ -1369,7 +1402,7 @@ static void shrink_worker(struct work_struct *w) > goto resched; > } > > - ret = shrink_memcg(memcg); > + ret = shrink_memcg(memcg, NR_ZSWAP_WB_BATCH); > /* drop the extra reference */ > mem_cgroup_put(memcg); > > @@ -1493,7 +1526,7 @@ bool zswap_store(struct folio *folio) > objcg = get_obj_cgroup_from_folio(folio); > if (objcg && !obj_cgroup_may_zswap(objcg)) { > memcg = get_mem_cgroup_from_objcg(objcg); > - if (shrink_memcg(memcg)) { > + if (shrink_memcg(memcg, 1)) { Why 64 for the global limit but only 1 for the cgroup limit? That seems arbitrary in multiple ways. Direct reclaim, kswapd, proactive reclaim, cgroup limit reclaim use SWAP_CLUSTER_MAX for the batch size near-universally. It's magic too to be sure, but at least you wouldn't have to make up new magic? Otherwise, the patch looks good to me.