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a=rsa-sha256; c=relaxed/relaxed; d=stgolabs.net; s=dreamhost; t=1741884276; bh=uET1fL+vCM9Q2BqQovUvW0LaxkIi96OCoOTgYKD4kNs=; h=Date:From:To:Cc:Subject:Content-Type; b=YvvdCLc1kVsaBV6jfPuOqoT1z0NXccBok/ZWrKs2pZoBMyobB7YXqhMQGUUgdgCmP jddpF+H+hCHV9hlsySR7Y1gB8UjCy7mqCZEArYUDqcm72k+4YhRy4oVEG6K1j631UI 5KnOU7pEqZTTqbtWIEPoYoDe6SyEINiME18debvKgWpVUZ+I8CS3NmRCOMYiLyAZqF aBYaECdLnxafRckV04c35NZnfM+BwQ6/2722+XOLfq2mjtpchJWR6MLSJd7ZPOcVjl mSu9ko0HC/YvVbNshqiyVg1QXghLkNfxVcups9r0eIvc5ATiy0AJsOf/os4T0GZQc2 av840qcTFr8TA== Date: Thu, 13 Mar 2025 09:44:30 -0700 From: Davidlohr Bueso To: Bharata B Rao Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, AneeshKumar.KizhakeVeetil@arm.com, Hasan.Maruf@amd.com, Jonathan.Cameron@huawei.com, Michael.Day@amd.com, akpm@linux-foundation.org, dave.hansen@intel.com, david@redhat.com, feng.tang@intel.com, gourry@gourry.net, hannes@cmpxchg.org, honggyu.kim@sk.com, hughd@google.com, jhubbard@nvidia.com, k.shutemov@gmail.com, kbusch@meta.com, kmanaouil.dev@gmail.com, leesuyeon0506@gmail.com, leillc@google.com, liam.howlett@oracle.com, mgorman@techsingularity.net, mingo@redhat.com, nadav.amit@gmail.com, nphamcs@gmail.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, rppt@kernel.org, shivankg@amd.com, shy828301@gmail.com, sj@kernel.org, vbabka@suse.cz, weixugc@google.com, willy@infradead.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, yuanchu@google.com, hyeonggon.yoo@sk.com Subject: Re: [RFC PATCH 2/4] mm: kpromoted: Hot page info collection and promotion daemon Message-ID: <20250313164430.bzkfyqmx6a5dj7d2@offworld> Mail-Followup-To: Bharata B Rao , linux-kernel@vger.kernel.org, linux-mm@kvack.org, AneeshKumar.KizhakeVeetil@arm.com, Hasan.Maruf@amd.com, Jonathan.Cameron@huawei.com, Michael.Day@amd.com, akpm@linux-foundation.org, dave.hansen@intel.com, david@redhat.com, feng.tang@intel.com, gourry@gourry.net, hannes@cmpxchg.org, honggyu.kim@sk.com, hughd@google.com, jhubbard@nvidia.com, k.shutemov@gmail.com, kbusch@meta.com, kmanaouil.dev@gmail.com, leesuyeon0506@gmail.com, leillc@google.com, liam.howlett@oracle.com, mgorman@techsingularity.net, mingo@redhat.com, nadav.amit@gmail.com, nphamcs@gmail.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, rppt@kernel.org, shivankg@amd.com, shy828301@gmail.com, sj@kernel.org, vbabka@suse.cz, weixugc@google.com, willy@infradead.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, yuanchu@google.com, hyeonggon.yoo@sk.com References: <20250306054532.221138-1-bharata@amd.com> <20250306054532.221138-3-bharata@amd.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; format=flowed Content-Disposition: inline In-Reply-To: <20250306054532.221138-3-bharata@amd.com> User-Agent: NeoMutt/20220429 On Thu, 06 Mar 2025, Bharata B Rao wrote: >+static int page_should_be_promoted(struct page_hotness_info *phi) >+{ >+ struct page *page = pfn_to_online_page(phi->pfn); >+ unsigned long now = jiffies; >+ struct folio *folio; >+ >+ if (!page || is_zone_device_page(page)) >+ return false; >+ >+ folio = page_folio(page); >+ if (!folio_test_lru(folio)) { >+ count_vm_event(KPROMOTED_MIG_NON_LRU); >+ return false; >+ } >+ if (folio_nid(folio) == phi->hot_node) { >+ count_vm_event(KPROMOTED_MIG_RIGHT_NODE); >+ return false; >+ } How about using the LRU age itself: if (folio_test_active()) return true; >+ >+ /* If the page was hot a while ago, don't promote */ >+ if ((now - phi->last_update) > 2 * msecs_to_jiffies(KPROMOTED_FREQ_WINDOW)) { >+ count_vm_event(KPROMOTED_MIG_COLD_OLD); >+ return false; >+ } >+ >+ /* If the page hasn't been accessed enough number of times, don't promote */ >+ if (phi->frequency < KPRMOTED_FREQ_THRESHOLD) { >+ count_vm_event(KPROMOTED_MIG_COLD_NOT_ACCESSED); >+ return false; >+ } >+ return true; >+} ... >+static int kpromoted(void *p) >+{ >+ pg_data_t *pgdat = (pg_data_t *)p; >+ struct task_struct *tsk = current; >+ long timeout = msecs_to_jiffies(KPROMOTE_DELAY); >+ >+ const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); >+ >+ if (!cpumask_empty(cpumask)) >+ set_cpus_allowed_ptr(tsk, cpumask); Explicit cpumasks are not needed if you use kthread_create_on_node(). See https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c6a566f6c1b4d5dff659acd221f95a72923f4085 >+ >+ while (!kthread_should_stop()) { >+ wait_event_timeout(pgdat->kpromoted_wait, >+ kpromoted_work_requested(pgdat), timeout); >+ kpromoted_do_work(pgdat); >+ } >+ return 0; >+} >+ >+static void kpromoted_run(int nid) >+{ >+ pg_data_t *pgdat = NODE_DATA(nid); >+ >+ if (pgdat->kpromoted) >+ return; >+ >+ pgdat->kpromoted = kthread_run(kpromoted, pgdat, "kpromoted%d", nid); >+ if (IS_ERR(pgdat->kpromoted)) { >+ pr_err("Failed to start kpromoted on node %d\n", nid); >+ pgdat->kpromoted = NULL; >+ } >+} >+