Re: PHP performance on Xen domU with mulitple vcpu

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

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

> 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.

-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost