Re: [Xen-devel] [PATCH v3] tools/libxc: Batch memory allocations for PV guests

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2015-06-17 at 12:22 +0100, Ross Lagerwall wrote:
> On 06/17/2015 12:14 PM, Ian Campbell wrote:
> > On Mon, 2015-06-15 at 17:08 +0100, Wei Liu wrote:
> >> On Mon, Jun 15, 2015 at 11:12:07AM +0100, Ross Lagerwall wrote:
> >>> The current code for allocating memory for PV guests batches the
> >>> hypercalls to allocate memory by allocating 1024*1024 extents of order 0
> >>> at a time. To make this faster, first try allocating extents of order 9
> >>> (2 MiB) before falling back to the order 0 allocating if the order 9
> >>> allocation fails.
> >>>
> >>> On my test machine this reduced the time to start a 128 GiB PV guest by
> >>> about 60 seconds.
> >
> >  From 61s or from 600s?
> 
> It reduced the total time _by_ 60 seconds.

I know, my question was whether 60s was a significant or insignificant
fraction of the time take to start a guest. Seems like it was pretty
significant.

>  I think it takes about 10 
> seconds to start the guest now, but it is not related to the size of 
> guest memory.
> 
> Regards



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