[Xen-devel] checkLiveMigrateMemory() insufficient?

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

I occassionally see failures live migrating due to running out of memory in
sh_set_allocation(). For example on a 4Gb machine with freely-balloonable dom0,
the routine attempts to allocate 1536 pages of heap, and fails right at the
end:

(xVM) free 5dc total 5dc xenheap 21 total 40000 max 40000
(xVM) failed to allocate shadow pages from domheap

This is a 64-bit guest on 64-bit host. I see this in xend.log:

[2008-10-01 08:56:31 100921] DEBUG (XendDomainInfo:2121) overhead_kb is now 9216
[2008-10-01 08:56:31 100921] DEBUG (balloon:116) Balloon: 12216 KiB free; need 
9216; done.

(Note that I added an extra 1Mb on to the normal overhead_kb allocation).

So we have 12Mb free from physinfo, and we're trying to allocate 6Mb plus some
other smaller allocations. I suspect the issue is one of fragmentation of the
heap? That is, no allocations of order SHADOW_MAX_ORDER could be found?

Does the linux balloon handler free in page-sized increments like Solaris
currently does?

Is there a better way to handle this?

regards
john

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel