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Fri, 11 Apr 2025 08:29:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id KsxFBuHS+GeAFAAAD6G6ig (envelope-from ); Fri, 11 Apr 2025 08:29:21 +0000 Date: Fri, 11 Apr 2025 10:29:04 +0200 From: Oscar Salvador To: Gavin Shan Cc: David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, adityag@linux.ibm.com, donettom@linux.ibm.com, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, akpm@linux-foundation.org, shan.gavin@gmail.com Subject: Re: [PATCH] drivers/base/memory: Avoid overhead from for_each_present_section_nr() Message-ID: References: <20250410125110.1232329-1-gshan@redhat.com> <9deb3725-8991-43d1-8c3d-56523fabff28@redhat.com> <44dff493-9d79-4343-ba81-0c262d7a5b4e@redhat.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: <44dff493-9d79-4343-ba81-0c262d7a5b4e@redhat.com> X-Spam-Score: -2.80 X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[99.99%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_SEVEN(0.00)[11]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[redhat.com,kvack.org,vger.kernel.org,linux.ibm.com,linuxfoundation.org,kernel.org,linux-foundation.org,gmail.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Level: On Fri, Apr 11, 2025 at 03:04:16PM +1000, Gavin Shan wrote: > I think it's a good point. Tried a quick test on a ARM64 machine whose memory > capacity is 1TB. Leaping 'nr' by 'sections_per_block' improves the performance a bit, > even it's not too much. The time taken by memory_dev_init() drops from 110ms to 100ms. > For the IBM Power9 machine (64GB memory) I have, there are not too much space to be > improved because the time taken by memory_dev_init() is only 10ms. I will post a patch > for review after this patch gets merged, if you agree. I have a patch that looked pretty much the same because I wanted to try it out after commenting it to David, to see the "gains". On a x86 system with 100GB and memory-blocks spanning 8 sections, I saw a gain of 12us. Of course, that kinda of accumulates wrt. memory capacity. -- Oscar Salvador SUSE Labs