[Xen-devel] XEN PV Linux performance

[Zhou Jacky <jackyzt98@xxxxxxxxx>]

I re-post this from Xen-User maillist.

I found that xen PV linux performance is very poor comparing with native linux or HVMPV linux in some case such as system call (which will cause context switch).

Here is a very simple sample:

double geTime() {

        struct timeval t;

        gettimeofday(&t, 0);

        return (double) t.tv_sec + (double) t.tv_usec / 1000000.0;

}

int geInc(int sum) {

       return sum+1;

}

int main() {

       for (i=0; i<; i++) {

     geTime();

}

In PV linux guest, It will be 10 times slower than PVHVM linux guest.  While call getInc()  10000000 times, PV guest is a little faster then HVMPV.

So it seems that PV linux guest has poor performance in context switch case.

How can I tune this or if there's any plan fixing this issue? 

I'm looking forward to get your feedback. Thank you.

---------------------------------------------------------------------------

XEN 4.1.2 + Dom 0 kernel 3.2 + Ubuntu 12.04 guest,  Intel(R) Xeon(R) CPU E5620

Jacky

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