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SubjectRe: [PATCH 1/3] mm/page_alloc: factor out setting of pcp->high and pcp->batch.
On 04/06/2013 06:37 PM, Simon Jeons wrote:
> Hi Cody,
> On 04/06/2013 04:33 AM, Cody P Schafer wrote:
>> Creates pageset_set_batch() for use in setup_pageset().
>> pageset_set_batch() imitates the functionality of
>> setup_pagelist_highmark(), but uses the boot time
>> (percpu_pagelist_fraction == 0) calculations for determining ->high
>
> Why need adjust pcp->high, pcp->batch during system running? What's the
> requirement?
>

There is currently a sysctl (which I patch later in this series) which
allows adjusting the ->high mark (and, indirectly, ->batch).
Additionally, memory hotplug changes ->high and ->batch due to the zone
size changing (essentially, zone->managed_pages and zone->present_pages
have changed) , meaning that zone_batchsize(), which is used at boot to
set ->batch and (indirectly) ->high has a different output.

Note that in addition to the 2 users of this functionality mentioned
here, I'm currently working on anther resizer of zones (runtime NUMA
reconfiguration).



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