Messages in this thread | | | Date | Wed, 29 Jun 2011 15:18:52 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v2 19/22] KVM: MMU: lockless walking shadow page table |
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On 06/29/2011 02:50 PM, Xiao Guangrong wrote: > >> > > >> > I think we should do this unconditionally. The cost of ping-ponging the shared cache line containing reader_counter will increase with large smp counts. On the other hand, zap_page is very rare, so it can be a little slower. Also, less code paths = easier to understand. > >> > > >> > >> On soft mmu, zap_page is very frequently, it can cause performance regression in my test. > > > > Any idea what the cause of the regression is? It seems to me that simply deferring freeing shouldn't have a large impact. > > > > I guess it is because the page is freed too frequently, i have done the test, it shows > about 3219 pages is freed per second > > Kernbench performance comparing: > > the origin way: 3m27.723 > free all shadow page in rcu context: 3m30.519
I don't recall seeing such a high free rate. Who is doing all this zapping?
You may be able to find out with the function tracer + call graph.
-- error compiling committee.c: too many arguments to function
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