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[Xen-devel] RE: Memory fragmentation, order>0 allocation, and 4.0 dynami

To: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Subject: [Xen-devel] RE: Memory fragmentation, order>0 allocation, and 4.0 dynamic RAM optimization features
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 18 Feb 2010 16:18:53 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Tim Deegan <Tim.Deegan@xxxxxxxxxx>, GeorgeDunlap <george.dunlap@xxxxxxxxxxxxx>, PatrickColp <pjcolp@xxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, Andrew Peace <Andrew.Peace@xxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, Grzegorz Milos <gm281@xxxxxxxxx>
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>>> Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> 18.02.10 17:09 >>>
>But ignoring my flimsy excuses, Jan, do you have some debug code
>you are using to identify order>0 allocations?  If so, could I
>have a copy... and perhaps Keir would consider adding
>it post-4.0 to make it easier to search-and-destroy.

I actually noticed this only as a side effect from a much uglier debugging
patch - observing apparent memory corruption with no apparent pattern
during save/restore/migrate, I finally decided to try a brute force method
and track all allocations. Since you are so eager to point out and fix all
order > 0 allocations, I was quite surprised to see one while tmem
itself initialized its state for Dom0. Hence I thought I'd point it out. The
patch as it stands is, I think, not really a general debugging aid - if you
think differently, I can of course still share it.

Jan


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