linux-kernel - Re: [Xen-devel] Re: [PATCH] Two patches fixing regression introduced by 'x86-64, mm: Put early page table high'

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Date:	Mon, 02 May 2011 12:59:08 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	yinghai@...nel.org,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] Re: [PATCH] Two patches fixing regression introduced
 by 'x86-64, mm: Put early page table high'

On 05/02/2011 12:34 PM, Konrad Rzeszutek Wilk wrote:
> On Mon, May 02, 2011 at 11:33:16AM -0700, H. Peter Anvin wrote:
>> On 05/02/2011 11:08 AM, Konrad Rzeszutek Wilk wrote:
>>>>
>>>> My inclination would be to apply your workaround -- are there any
>>>> adverse effects to doing that?
>>>
>>> There is a bootup slowdown (not noticeable). That is because we call the
>>> 'memblock_find_range' function on every PTE table creation (only during
>>> bootup of course). 
>>>
>>> Testing wise, on the machines on which the regression occurred, with these two
>>> patches the regression disappears - so that is a good sign. I am testing
>>> it on some more today to assure myself I am not missing anything.
>>>
>>
>> OK, sounds like a plan then.  I like it because it doesn't affect the
>> native kernel.
> 
> <laughs> I figured :-)
> 
> Moving forward I really want to get rid of this wart.
> 
> Not sure if it is possible, but I was thinking it would be nice to get
> you, Yinghai, Jeremy, Stefano all in one place (phone or web-conference thing)
> to sketch out some ideas and hammer something out.
> 
> What days would work best?

First things first... are you pushing the workaround (you can add my
Acked-by:) or should I?

Second... I don't know what physical locations and/or time zones every
one is in, which is probably the first thing.

Third, I will be travelling a lot over the next two weeks, plus we are
getting close to merge window time, so it might be hard to schedule
before the merge window.  Are you looking at trying to push something
for .40?  If so, you probably should have an implementation in mind
already.  If not, I suggest we aim for after the merge window is over or
at least quieted down.
	
	-hpa
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