Re: PHP performance on Xen domU with mulitple vcpu
Greg Troxel <[email protected]>
| Newsgroups | gmane.os.netbsd.devel.kernel |
|---|---|
| Message-ID | <[email protected]> |
Emmanuel Dreyfus <[email protected]> writes: > On Thu, Apr 03, 2025 at 11:00:50AM -0400, Greg Troxel wrote: >> Have you written a test program to log and examined the return values? > > I ran gettimeofday 1M time, it took 5.12, which is much faster than > what happens in PHP. Here is the distribution of results: > > count value > 239726 1743694322.907498 > 119400 1743694324.187487 > 327599 1743694325.467476 > 174425 1743694326.747465 > 138850 1743694328.027453 Wow, that is messed up! >> Is xen somehow using a timecounter that is incrementing in larger jumps? > > Oh, yes, good pick! I use kern.timecounter.hardware=clockinterrupt > because with xen_system_time the domU's ntpd is unable to keep in sync. > > With kern.timecounter.hardware=xen_system_time, the uniqid() test runs > at normal speed. It sounds then like the clockinterrupt timecounter is seriously broken. I guess someone(tm) needs to fix xen_system_time to be ok on MP.