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

From: Simon Jeons
Date: Tue Apr 09 2013 - 01:43:13 EST


Hi Cody,
On 04/09/2013 01:39 AM, Cody P Schafer wrote:
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.

Thanks for your explain. I'm curious about this sysctl, when need adjust the ->high, ->batch during system running except memory hotplug which will change zone size?


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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