Re: [PATCH 3/6] mm/page_alloc: Adjust pcp->high after CPU hotplug events

Vlastimil Babka
2021-05-28T11:08:45Z

On 5/25/21 10:01 AM, Mel Gorman wrote:
> The PCP high watermark is based on the number of online CPUs so the
> watermarks must be adjusted during CPU hotplug. At the time of
> hot-remove, the number of online CPUs is already adjusted but during
> hot-add, a delta needs to be applied to update PCP to the correct
> value. After this patch is applied, the high watermarks are adjusted
> correctly.
>
> # grep high: /proc/zoneinfo | tail -1
> high: 649
> # echo 0 > /sys/devices/system/cpu/cpu4/online
> # grep high: /proc/zoneinfo | tail -1
> high: 664
> # echo 1 > /sys/devices/system/cpu/cpu4/online
> # grep high: /proc/zoneinfo | tail -1
> high: 649
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

Acked-by: Vlastimil Babka <vbabka@suse.cz>