[Acked] [PATCH] [Vivid][SRU] hv_netvsc: Clean up two unused variables

[Jay Vosburgh]

Andy Whitcroft <apw at canonical.com> wrote:

>On Mon, Dec 07, 2015 at 05:07:35PM +0000, Andy Whitcroft wrote:
>> On Fri, Dec 04, 2015 at 06:56:08AM -0700, Tim Gardner wrote:
>> > On 12/04/2015 05:02 AM, Andy Whitcroft wrote:
>> > > On Fri, Dec 04, 2015 at 12:19:09PM +0900, Seyeong Kim wrote:
>> > >> From: Haiyang Zhang <haiyangz at microsoft.com>
>> > >>
>> > >> BugLink: http://bugs.launchpad.net/bugs/1521053
>> > >>
>> > >> The commit
>> > >>
>> > >> hv_netvsc: Clean up two unused variables
>> > > 
>> > > As this commit only removes unused variables, it is not at all clear how
>> > > this could cause or fix network slowdowns.  The net effect is to remove
>> > > 64 bytes from one structure, but this seems unlikely enough to cause
>> > > significant performance issues.
>> > > 
>> > > How was it determined that this was the fix?
>> > > 
>> > > -apw
>> > 
>> > I'm with Andy on this one. How does this really fix the problem ?
>> 
>> It is sounding like this does actually fix something.  For that to be
>> true this layout change would need to radically affect cache
>> performance.  But if the testing can be confirmed then it has my ack.
>> 
>> Acked-by: Andy Whitcroft <apw at canonical.com>
>
>Confirmed that removing these four bytes reduce the header size such
>that it fits into the standard packet headroom and we no longer have to
>copy the packet headers every time.

	We also would like to request that this patch be applied as an
SRU for the Wily kernel as well to avoid regression during upgrades.

	-J

---
	-Jay Vosburgh, jay.vosburgh at canonical.com