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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] VM memory allocation speed with cs 26056
On 11/13/2012 10:46 AM, Zhigang Wang wrote: > On 11/12/2012 01:25 PM, Keir Fraser wrote: >> On 12/11/2012 15:01, "Zhigang Wang" <zhigang.x.wang@xxxxxxxxxx> wrote: >> >>> Hi Keir/Jan, >>> >>> Recently I got a chance to access a big machine (2T mem/160 cpus) and I >>> tested >>> your patch: http://xenbits.xen.org/hg/xen-unstable.hg/rev/177fdda0be56 >>> >>> Attached is the result. >> The PVM result is weird, there is a small-ish slowdown for small domains, >> becoming a very large %age slowdown as domain memory increases, and then >> turning into a *speedup* as the memory size gets very large indeed. >> >> What are the error bars like on these measurements I wonder? One thing we >> could do to allow PV guests doing 4k-at-a-time allocations through >> alloc_heap_pages() to benefit from the TLB-flush improvements, is pull the >> filtering-and-flush out into populate_physmap() and increase_reservation(). >> This is listed as a todo in the original patch (26056). >> >> To be honest I don't know why the original patch would make PV domain >> creation slower, and certainly not by a varying %age depending on domain >> memory size! >> >> -- Keir > I did it second time. It seems the result (attached) is promising. > > I think the strange result is due to the order of testing: > start_physical_machine -> test_hvm -> test_pvm. > > This time, I did: start_physical_machine -> test_pvm -> test_hvm. > > You can see the pvm memory allocation speed is not affected by your patch > this time. > > So I believe this patch is excellent now. I get another chance to run the test without (old) and with (new) cs 25056 with order: start_physical_machine -> test_hvm -> test_pvm It seems PV guest memory allocation is not affected by this patch, although it makes a big difference if testing with order: start_physical_machine -> test_pvm -> test_hvm Thanks for the patch. Zhigang Attachment:
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