Messages in this thread |  | | Subject | Re: [v4] mm: khugepaged: avoid overriding min_free_kbytes set by user | From | Vijay Balakrishna <> | Date | Tue, 22 Sep 2020 09:10:46 -0700 |
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On 9/22/2020 3:07 AM, Michal Hocko wrote: > On Tue 22-09-20 10:07:26, Kirill A. Shutemov wrote: >> On Mon, Sep 21, 2020 at 12:07:23PM -0700, Vijay Balakrishna wrote: >>>> >>>> I would recommend reposting the patch which adds heuristic for THP (if >>>> THP is enabled) into the hotplug path, arguing with the consistency and >>>> surprising results when adding memory decreases the value. >>> >>> I hope my reposted patch >>> ([v3 1/2] mm: khugepaged: recalculate min_free_kbytes after memory hotplug >>> as expected by khugepaged) >>> change log is ok: >>> >>> When memory is hotplug added or removed the min_free_kbytes must be >>> recalculated based on what is expected by khugepaged. Currently >>> after hotplug, min_free_kbytes will be set to a lower default and higher >>> default set when THP enabled is lost. This change restores min_free_kbytes >>> as expected for THP consumers. >> >> Any scenario when hotremove would result in changing min_free_kbytes? > > init_per_zone_wmark_min is called from both online and offline path. But > I believe the problem is not in the offlining path. A decrease wrt > previous auto tuned value is to be expected. The primary problem is that > the hotadding memory after boot (without any user configured value) will > decrease the value effectively because khugepaged tuning > (set_recommended_min_free_kbytes) is not called.
Thank you Michal and Kirill.
Vijay >
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