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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> 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-Rspamd-Queue-Id: 4D9361C0004 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: pnsx615anbh58sqp76tfrb63ogiirxox X-HE-Tag: 1744360163-168797 X-HE-Meta: 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 2FCRGC7V +Yd12zJmhYrJlk4+XY070jrViLWlcw/FTwYGBxjgX0XH07giQG4RCSExzNSHGXgfzjZzULpohM/ZbW6E9GzCPYofXIff5GI+l61LRyZc2HCjkWSLlMnbwT3omNwVMwP1cgREwqzxdKMEoH99QHcEHk+B20pt5k7Ht8XADUFGv9qIChxFGgMi57La7w8FU+BOjZc6o87WNJvao8qP5Ollhb+TKf3coRwlHSwy/wnZr0QH19yPTTywZutyfdKzw5OHLGefpxGuziCwYh0TwXIJROQkfQWZr0LsLrcTa5GX+r/YFR/eprCEGmTAOvd4yD1lsFTOM386J3CMix4yXDu6UW/Mx41dfYIQv0y3UOAl11kPAen3cdqEraeZUYGLnIHfp5n3Z X-Bogosity: Ham, tests=bogofilter, spamicity=0.015666, 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 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