[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] slow live magration / xc_restore on xen4 pvops
On Thursday, 03 June 2010 at 06:47, Keir Fraser wrote: > On 03/06/2010 02:04, "Brendan Cully" <Brendan@xxxxxxxxx> wrote: > > > I've done a bit of profiling of the restore code and observed the > > slowness here too. It looks to me like it's probably related to > > superpage changes. The big hit appears to be at the front of the > > restore process during calls to allocate_mfn_list, under the > > normal_page case. It looks like we're calling > > xc_domain_memory_populate_physmap once per page here, instead of > > batching the allocation? I haven't had time to investigate further > > today, but I think this is the culprit. > > Ccing Edwin Zhai. He wrote the superpage logic for domain restore. Here's some data on the slowdown going from 2.6.18 to pvops dom0: I wrapped the call to allocate_mfn_list in uncanonicalize_pagetable to measure the time to do the allocation. kernel, min call time, max call time 2.6.18, 4 us, 72 us pvops, 202 us, 10696 us (!) It looks like pvops is dramatically slower to perform the xc_domain_memory_populate_physmap call! I'll attach the patch and raw data below. Attachment:
alloc-profile.diff Attachment:
2.6.18-alloc Attachment:
pvops-alloc _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |