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Re: [Qemu-devel] [PATCH V13 10/13] NUMA: add qmp command set-mem-policy
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH V13 10/13] NUMA: add qmp command set-mem-policy to set memory policy for NUMA node |
Date: |
Wed, 2 Oct 2013 23:13:29 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Sep 17, 2013 at 11:16:22AM +0800, Wanlong Gao wrote:
> This QMP command allows user set guest node's memory policy
> through the QMP protocol. The qmp-shell command is like:
> set-mem-policy nodeid=0 policy=membind relative=true host-nodes=0-1
>
> Reviewed-by: Luiz Capitulino <address@hidden>
> Signed-off-by: Wanlong Gao <address@hidden>
Wanlong Gao,
1)
Exposing mbind via QMP/HMP on a live guest is interesting because,
see mbind manpage:
"By default, mbind() only has an effect for new allocations;
if the pages inside the range have been already touched before
setting the policy, then the policy has no effect. This default
behavior may be overridden by the MPOL_MF_MOVE and
MPOL_MF_MOVE_ALL flags described below."
This means that executing set-mem-policy on a live guest is
unpredictable: it depends on which pages have been faulted in already.
Should the command be restricted to offline guests?
2)
Have you tested the patchset with hugetlbfs (-mem-path) backing ?
- Re: [Qemu-devel] [PATCH V13 10/13] NUMA: add qmp command set-mem-policy to set memory policy for NUMA node,
Marcelo Tosatti <=