Re: [PATCH v5 0/5] Add movablecore_map boot option
From: Tang Chen
Date: Wed Jan 16 2013 - 20:50:19 EST
On 01/17/2013 06:52 AM, H. Peter Anvin wrote:
On 01/16/2013 01:29 PM, Andrew Morton wrote:
Yes. If SRAT support is available, all memory which enabled hotpluggable
bit are managed by ZONEMOVABLE. But performance degradation may
occur by NUMA because we can only allocate anonymous page and page-cache
from these memory.
In this case, if user cannot change SRAT information, user needs a way to
select/set removable memory manually.
If I understand this correctly you mean that once SRAT parsing is
implemented, the user can use movablecore_map to override that SRAT
parsing, yes? That movablecore_map will take precedence over SRAT?
Yes,
Hi HPA, Andrew,
No, I don't think so. In my [PATCH v4 3/6], I checked if users specified the
unhotpluggable memory ranges, I will remove them from movablecore_map.map[].
So this option will not override SRAT.
It works like this:
hotpluggable ranges: |-----------------|
unhotpluggable ranges: |-----| |--------|
user specified ranges: |---| |--------------------|
movablecore_map.map[]: |------------|
Please refer to https://lkml.org/lkml/2012/12/19/53.
But in this v5 patch-set, I remove all SRAT related code. So this v5 users'
option will override SRAT.
Thanks. :)
but we still need a higher-level user interface which specifies
which nodes, not which memory ranges, should be movable. That is the
policy granularity that is actually appropriate for the administrator
(trading off performance vs reliability.)
-hpa
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