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Wysocki" , linux-kernel@vger.kernel.org, "open list:SUSPEND TO RAM" , Carsten Grohmann , stable@vger.kernel.org Subject: Re: [PATCH v4 1/3] mm, swap: speed up hibernation allocation and writeout Message-Id: <20260216134222.5ec936d6503e72348227c58d@linux-foundation.org> In-Reply-To: <20260216-hibernate-perf-v4-1-1ba9f0bf1ec9@tencent.com> References: <20260216-hibernate-perf-v4-0-1ba9f0bf1ec9@tencent.com> <20260216-hibernate-perf-v4-1-1ba9f0bf1ec9@tencent.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 46A7E20007 X-Stat-Signature: ink3fkqorer35ugmu4j8gcu8a9s9ht48 X-Rspam-User: X-HE-Tag: 1771278144-184240 X-HE-Meta: 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 C73uJ/MG 4LKid+CCkdtrWIvaWbjrwYed2nigh+C/tPNQfX+yNtPqnXH1mGVAii7Hz7J5D277hQlZ256mOjn/RsitYUGJGury2XuFV0SbV5Qar5he5yCGMD0pv9ArrIl8aGqHwoQvTk2+S5Q6yzrVuGVqMef6O8LClSB4g9C3WTEfGnice4swEwnfq74Eb8TLq3pX5Ur2Yt2VmzJkTYT6jpTii4NTRiy6CxlvJ1zi4a6NuCJYk6HFvOw5L17o4EAAiVj5pMv2MBYfXbLzgjpbyKdGBVnordTpPP+/iPFnoSRIMZ/R8JDvqKWB6dSoITUvN6M5cc+cNfppckEkXOvUNWNoGz8FGWS1uyVAzqj50heipeFQQT0+nlBZUEi1krMjjdEewflC6yFTi22pSUSDl1Ds= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 16 Feb 2026 22:58:02 +0800 Kairui Song via B4 Relay wrote: > From: Kairui Song > > Since commit 0ff67f990bd4 ("mm, swap: remove swap slot cache"), > hibernation has been using the swap slot slow allocation path for > simplification, which turns out might cause regression for some > devices because the allocator now rotates clusters too often, leading to > slower allocation and more random distribution of data. > > Fast allocation is not complex, so implement hibernation support as > well. > > Test result with Samsung SSD 830 Series (SATA II, 3.0 Gbps) shows the > performance is several times better [1]: > 6.19: 324 seconds > After this series: 35 seconds Thanks. I'll merge only [1/3] at this time, into mm-unstable at this time (I'll move it to mm-unstable after resyncing mm.git with upstream). We don't want the other two patches present during testing of this backportable fix because doing so partially invalidates that testing - [2/3] and[3/3] might accidentally fix issues which [1/3] added. It happens, occasionally. > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1926,8 +1926,9 @@ void swap_put_entries_direct(swp_entry_t entry, int nr) > /* Allocate a slot for hibernation */ > swp_entry_t swap_alloc_hibernation_slot(int type) > { > - struct swap_info_struct *si = swap_type_to_info(type); > - unsigned long offset; > + struct swap_info_struct *pcp_si, *si = swap_type_to_info(type); > + unsigned long pcp_offset, offset = SWAP_ENTRY_INVALID; > + struct swap_cluster_info *ci; > swp_entry_t entry = {0}; > > if (!si) > @@ -1937,11 +1938,21 @@ swp_entry_t swap_alloc_hibernation_slot(int type) > if (get_swap_device_info(si)) { > if (si->flags & SWP_WRITEOK) { > /* > - * Grab the local lock to be compliant > - * with swap table allocation. > + * Try the local cluster first if it matches the device. If > + * not, try grab a new cluster and override local cluster. > */ nanonit, worrying about 80-cols is rather old fashioned but there's no reason to overflow 80 in a block comment! > local_lock(&percpu_swap_cluster.lock); > - offset = cluster_alloc_swap_entry(si, NULL); > + pcp_si = this_cpu_read(percpu_swap_cluster.si[0]); > + pcp_offset = this_cpu_read(percpu_swap_cluster.offset[0]); > + if (pcp_si == si && pcp_offset) { > + ci = swap_cluster_lock(si, pcp_offset); > + if (cluster_is_usable(ci, 0)) > + offset = alloc_swap_scan_cluster(si, ci, NULL, pcp_offset); > + else > + swap_cluster_unlock(ci); > + } > + if (!offset) > + offset = cluster_alloc_swap_entry(si, NULL); > local_unlock(&percpu_swap_cluster.lock); > if (offset) > entry = swp_entry(si->type, offset);