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Re: [Xen-devel] [PATCH 3/6] xen-gntdev: Remove unneeded structures from grant_map tracking data
On 12/14/2010 01:52 PM, Daniel De Graaf wrote:
> On 12/14/2010 04:15 PM, Jeremy Fitzhardinge wrote:
>> On 12/14/2010 06:55 AM, Daniel De Graaf wrote:
>>> The entire hypercall argument list isn't required; only selected
>>> fields from the hypercall need to be tracked between the ioctl, map,
>>> and unmap operations.
>> Is the rationale of this patch to save memory? If so, how much does it
>> (This patch seems sensible in principle, but it doesn't seem to save
>> much complexity.)
> This will also allow easier testing of what pages need to be unmapped
> (more obvious in the HVM version). I also find it less confusing to
> populate the hypercall arguments immediately before the hypercall, but
> that's likely a matter of opinion. It only saves 46 bytes per page, so
> if it seems more complex it could be dropped.
I like it in general. See the other mail I just sent - you can use the
multicall API to remove all the allocations for the arguments, and that
should help a lot.
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