[libvirt] [ROC] migration: set cpu throttle value by workload

[Chen Hanxiao]

At 2017-04-26 19:26:53, "Chao Fan" <fanc.fnst at cn.fujitsu.com> wrote:
>Hi all,
>
>When migrating a guest which consumes too much CPU & memory, dirty
>pages amount will increase significantly, so does the migration
>time, migration can not even complete, at worst.
>
>So I made an RFC patch in QEMU to set cpu throttle value by workload
>when migration. The test result and the RFC patch are here:
>https://lists.gnu.org/archive/html/qemu-devel/2017-01/msg03479.html
>
>But this idea was not accepted by QEMU community. So I want to do a
>similar feature in libvirt:

Hi, Fan
>
>Step 1: Add --auto-converge-smart parameter to migrate.
>Step 2: Add a timer in qemu-driver to get the 'info migrate' to check
>        if the dirty-pages-rate updated every 1 second or 0.5 second
>	when migration.
>Step 3: If updated, change the cpu throttle value according to the
>        dirty-pages-rate and page-size by
>        'migrate_set_parameter cpu-throttle-increment'

If dirty-pages-rate rising, we increase cpu-throttle-increment;
if it falling after a while,
would we  decrease cpu-throttle-increment then?

Regards,
- Chen

>
>I think this feature makes auto-converge smarter than leaving the
>cpu throttle value with default 20/10 or set by users.
>And also it can save time.
>
>Any comments will be welcome.




>
>Thanks,
>Chao Fan
>
>
>
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