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Re: [qemu-s390x] [PATCH 2/3] qmp: add query-cpus-fast
From: |
David Hildenbrand |
Subject: |
Re: [qemu-s390x] [PATCH 2/3] qmp: add query-cpus-fast |
Date: |
Mon, 12 Feb 2018 21:35:28 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 12.02.2018 13:14, Viktor Mihajlovski wrote:
> From: Luiz Capitulino <address@hidden>
>
> The query-cpus command has an extremely serious side effect:
> it always interrupts all running vCPUs so that they can run
> ioctl calls. This can cause a huge performance degradation for
> some workloads. And most of the information retrieved by the
> ioctl calls are not even used by query-cpus.
>
> This commit introduces a replacement for query-cpus called
> query-cpus-fast, which has the following features:
>
> o Never interrupt vCPUs threads. query-cpus-fast only returns
> vCPU information maintained by QEMU itself, which should be
> sufficient for most management software needs
>
> o Make "halted" field optional: we only return it if the
> halted state is maintained by QEMU. But this also gives
> the option of dropping the field in the future (see below)
>
If I'm not wrong, this comment is superseded by ...
> o Drop irrelevant fields such as "current", "pc" and "arch"
>
> o Drop field "halted" since it can't be provided fast reliably
> and is too volatile on most architectures to be really useful
>
this comment :)
> o Rename some fields for better clarification & proper naming
> standard>
> Signed-off-by: Luiz Capitulino <address@hidden>
> Signed-off-by: Viktor Mihajlovski <address@hidden>
Wondering if we could tweak the old interface with a simple flag "fast =
true".
--
Thanks,
David / dhildenb
- Re: [qemu-s390x] [PATCH 1/3] qmp: expose s390-specific CPU info, (continued)
Re: [qemu-s390x] [PATCH 1/3] qmp: expose s390-specific CPU info, David Hildenbrand, 2018/02/12
[qemu-s390x] [PATCH 2/3] qmp: add query-cpus-fast, Viktor Mihajlovski, 2018/02/12
[qemu-s390x] [PATCH 3/3] qmp: add architecture specific cpu data for query-cpus-fast, Viktor Mihajlovski, 2018/02/12
Re: [qemu-s390x] [PATCH 3/3] qmp: add architecture specific cpu data for query-cpus-fast, Luiz Capitulino, 2018/02/12
Re: [qemu-s390x] [PATCH 0/3] add query-cpu-fast and related s390 changes, Cornelia Huck, 2018/02/12