Re: [PATCH 1/3] mm/page_alloc: factor out setting of pcp->high andpcp->batch.

[Cody P Schafer]

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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