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Mon, 29 Jun 2026 18:18:25 -0700 (PDT) Message-ID: Date: Tue, 30 Jun 2026 09:18:06 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [PATCH v5 2/6] mm/zswap: Support batch writeback in shrink_memcg() To: Yosry Ahmed Cc: akpm@linux-foundation.org, tj@kernel.org, hannes@cmpxchg.org, shakeel.butt@linux.dev, mhocko@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 References: <20260629112032.20423-1-jiahao.kernel@gmail.com> <20260629112032.20423-3-jiahao.kernel@gmail.com> From: Hao Jia In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026/6/30 08:21, Yosry Ahmed wrote: > On Mon, Jun 29, 2026 at 07:20:28PM +0800, Hao Jia wrote: >> >> static void shrink_worker(struct work_struct *w) >> { >> struct mem_cgroup *memcg; >> - int ret, failures = 0, attempts = 0; >> + int failures = 0, attempts = 0; >> unsigned long thr; >> + long ret; >> >> /* Reclaim down to the accept threshold */ >> thr = zswap_accept_thr_pages(); >> @@ -1373,7 +1422,7 @@ 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); >> >> @@ -1394,7 +1443,7 @@ static void shrink_worker(struct work_struct *w) >> } >> ++attempts; >> >> - if (ret && ++failures == MAX_RECLAIM_RETRIES) >> + if (ret <= 0 && ++failures == MAX_RECLAIM_RETRIES) >> break; >> resched: >> cond_resched(); >> @@ -1504,7 +1553,7 @@ 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, num_node_state(N_NORMAL_MEMORY)) <= 0) { > > Why not just 1? > > I guess the current behavior will try each node. But this doesn't really > match it, as we may reclaim everything from the first node. Right? > Yes, it just keeps the number the same as before, but the behavior is not exactly the same. > I think it's probably fine to just do 1 here, fairness is not the main > concern in this code path, we're really just trying to free up some > space to free up some space for the incoming page. I doubt these limits > are actually being used extensively anyway, so we can revisit this later > if needed. Okay, I'll do this in the next version. Thanks, Hao > >> mem_cgroup_put(memcg); >> goto put_objcg; >> } >> -- >> 2.34.1 >>