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egZ3kfNdpMih8gvt73YF4vPha2W4p3/aOeMawIVxsddOoOMAedhcwC0ovFX8EBeTopqdMrHj0+m7FciLqRbU1u68BsIbXvVYUeyIu9LvaICkxajdCZH7havHSERQAKjve9axLvwYwHbkefQZtTbPqtTY9bpO4FkJSZlEkqcxKVm0FCHI= 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: Hi SeongJae and Sang-Heon, On 8/2/2025 1:50 AM, SeongJae Park wrote: > On Sat, 2 Aug 2025 01:11:09 +0900 Sang-Heon Jeon wrote: > >> Hi, Honggyu >> >> On Fri, Aug 1, 2025 at 8:35 PM Honggyu Kim wrote: >>> >>> Hi Sang-Heon and SeongJae, >>> >>> On 8/1/2025 2:58 AM, SeongJae Park wrote: >>>> Hello Sang-Heon, >>>> >>>> On Thu, 31 Jul 2025 22:22:30 +0900 Sang-Heon Jeon wrote: >>>> >>>>> Nowadays, damos operation actions support more various operation set. >>>>> But comments(also, generated documentation) doesn't updated. >>>>> So, fix the comments with current support status. > [...] >>>>> diff --git a/include/linux/damon.h b/include/linux/damon.h > [...] >>>>> * @DAMOS_WILLNEED: Call ``madvise()`` for the region with MADV_WILLNEED. >>>>> * @DAMOS_COLD: Call ``madvise()`` for the region with MADV_COLD. >>>>> - * @DAMOS_PAGEOUT: Call ``madvise()`` for the region with MADV_PAGEOUT. >>>>> + * @DAMOS_PAGEOUT: Reclaim the region. >>>> >>>> Nice! >>> >>> But doesn't it make confusion about whether this pages out to disk or does >>> demotion to the lower tier memory? It's because PAGEOUT action doesn't do >>> demotion, but it looks "reclaim" includes pageout and demotion together in my >>> understanding since /sys/kernel/mm/numa/demotion_enabled was introduced. > > To my understanding, DAMOS_PAGEOUT can also do demotion when demotion_enabled > is set. Am I missing something? Actually no, please see below. do_demote_pass in shrink_folio_list() https://github.com/torvalds/linux/blob/v6.16/mm/vmscan.c#L1122 The do_demote_pass is used here. https://github.com/torvalds/linux/blob/v6.16/mm/vmscan.c#L1293-L1302 can_demote() implementation returns false when demotion_enabled is on. https://github.com/torvalds/linux/blob/v6.16/mm/vmscan.c#L350-L351 The replated commit is as follows. mm/migrate: add sysfs interface to enable reclaim migration https://github.com/torvalds/linux/commit/20b51af15e014cac63b58a4f8b8b323ac35bccce > >> >> My intention was just to synchronize with the Design documentation. >> >> So how about changing the description to `Page out the region`, Would >> this be also confusing? >> I feel like it would be clearer than using word "reclaim" I don't have a good idea but it looks like recusive explanation. > > In my opinion, "reclaim" is good. I wish there could be better term that distinguishes between swap out and demotion. In my understanding "reclaim" includes both swap out and demotion. I also found that man page explanation about MADV_PAGEOUT is "reclaim these pages". If this is correct, then maybe demotion isn't included in "reclaim". Thanks, Honggyu