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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
