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Re: [Qemu-devel] [PATCH v7 21/42] postcopy: OS support test
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v7 21/42] postcopy: OS support test |
Date: |
Mon, 13 Jul 2015 17:31:26 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Juan Quintela (address@hidden) wrote:
> "Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> >
> > Provide a check to see if the OS we're running on has all the bits
> > needed for postcopy.
> >
> > Creates postcopy-ram.c which will get most of the other helpers we need.
> >
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
>
> Reviewed-by: Juan Quintela <address@hidden>
>
> I am guessing that test is ok, but we are doing the test each time that
> we change the function. We always end calling that kind of functions in
> several places. Shouldn't be good to rename the function to
> __postcopy_ram_supported_by_host()
>
> and do a toplevel function that is:
>
> bool postcopy_ram_supported_by_host(void)
> {
> static bool first_time = true;
> static supported = false;
>
> if (firt_time) {
> first_time = false;
> supported = __postcopy_ram_supported_by_host()
> }
> return supported;
> }
>
> Notice that I don't know how slow the mmap + usefault thing is, but I
> guess that the values would not change while running, no?
Since we only call this once, at the start of an incoming migration,
it seems overkill to do that.
Dave
>
> It has a review-by because I don't see anything wrong with it.
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK