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charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20230826153617.4019189-5-shikemeng@huaweicloud.com> X-Rspamd-Queue-Id: 5BD88A005B X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 83k8quoegm6qubxpxzcghu4dzrar1rt8 X-HE-Tag: 1693321317-534416 X-HE-Meta: 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 aF0J17Mi mrWDwO9QbFWJEUrJYS6pndD/6AZP8lHEUbjmAYXcP9b9fJ7FI0q7I9gS93iJFTA2d4oivM1Fr39hSVVffms9ZCnxSOix5IYMmd8lJbAmSZc/1HiE2Y3yadO1siE4IoO0kzyJQUnbKq6CHRZtUz41/BRYMXthz0Wbf1EgBlz7BLlYhGKV4SJPr1+MO3Ok22vDSnS/8QFyO2S/n7eepLbHS0wsFfNVU686xO17d3kB1VkIgzgY/nuIdHknfLaTcbJ4hxA134N/JXGBusRVI0bptZjOnN/06Aa0+9jEUUpZ0j3VYR1Y= 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: On Sat, Aug 26, 2023 at 11:36:14PM +0800, Kemeng Shi wrote: > We call isolate_freepages_block in strict mode, continuous pages in > pageblock will be isolated if isolate_freepages_block successed. > Then pfn + isolated will point to start of next pageblock to scan > no matter how many pageblocks are isolated in isolate_freepages_block. > Use pfn + isolated as start of next pageblock to scan to simplify the > iteration. > > The pfn + isolated always points to start of next pageblock as: > In case isolated buddy page has order higher than pageblock: > 1. page in buddy page is aligned with it's order > 2. order of page is higher than pageblock order > Then page is aligned with pageblock order. So pfn of page and isolated > pages count are both aligned pageblock order. So pfn + isolated is > pageblock order aligned. > > In case isolated buddy page has order lower than pageblock: > Buddy page with order N contains two order N - 1 pages as following: > | order N | > |order N - 1|order N - 1| > So buddy pages with order N - 1 will never cross boudary of order N. > Similar, buddy pages with order N - 2 will never cross boudary of order > N - 1 and so on. Then any pages with order less than pageblock order > will never crosa boudary of pageblock. > > Signed-off-by: Kemeng Shi > Reviewed-by: Baolin Wang While I don't think the patch is wrong, I also don't think it meaningfully simplifies the code or optimises enough to be justified. Even though a branch is eliminated, the whole path is not cheap. -- Mel Gorman SUSE Labs