Re: [Xen-devel] [PATCH] TSC scaling for live migration between platforms with different TSC frequecies

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Thu, Jun 18, 2009 at 01:57:21PM -0700, Dan Magenheimer wrote:

> > # dtrace -n 'fbt::tsc_gethrtime:entry /cpu == 0/ { @ = 
> > sum(1); }' -c "sleep 10"
> > dtrace: description 'fbt::tsc_gethrtime:entry ' matched 1 probe
> > dtrace: pid 29708 has exited
> > 
> >             27798
> > 
> > This is on a basically idle 8-way system. (The other CPUs are 
> > less busy.)
> 
> Just checking... this is in 10 seconds and each processor is
> "ticking" (and possibly a system-wide timer tick as well),
> so this is ~350 rdtsc/sec/processor, correct?

No. That's CPU0 only ('cpu == 0'). Solaris only has one system-wide
timer tick. This is mstate accounting: every kernel/user boundary, every
interrupt, etc. incurs at least one TSC read. (And of course the machine
is idle.)

regards
john

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel