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Re: [Qemu-devel] [PATCH v8 3/8] tests: Add migration xbzrle test
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v8 3/8] tests: Add migration xbzrle test |
Date: |
Tue, 8 May 2018 16:38:40 +0100 |
User-agent: |
Mutt/1.9.5 (2018-04-13) |
* Juan Quintela (address@hidden) wrote:
> "Dr. David Alan Gilbert" <address@hidden> wrote:
> > * Juan Quintela (address@hidden) wrote:
> >> Signed-off-by: Juan Quintela <address@hidden>
> >> Reviewed-by: Peter Xu <address@hidden>
>
> >> +
> >> + migrate_set_parameter(from, "xbzrle-cache-size", "33554432");
> >
> > I still worry about the cache size relative to the size of memory we're
> > actually changing in the test; I don't quite understand why it's turning
> > out to get lots of hits.
>
> I planned this as a smorke test. But what value do you have in mind?
Given the test code dirties 100MB of RAM, I suggest a cache of 110MB
say. But it's interesting that the stats show we are getting a lot of
page hits; I'm not sure I understand why.
> > Also, xbzrle eats so much CPU we'll still have to watch out for the low
> > end CPUs.
>
> Any concrete suggestion?
>
> My plan would have been to push on my next pull request:
>
> Add migration precopy test
> Add migration xbzrle test
> Migration ppc now inlines its program
>
> And put the rest of the patches with fixes for another review.
Go with it and lets see; if we hit problems then we can just turn that
300ms downtime limit right up.
Dave
>
> Later, Juan.
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK