| 1 |
On Apr 12, 2012 9:46 PM, "Konstantin" <konstantin@××××××××.com> wrote: |
| 2 |
> |
| 3 |
> Hello Pandu, |
| 4 |
> |
| 5 |
> |
| 6 |
> If you mean Tickless System (Dynamic Ticks) as NO_HZ=y so it already |
| 7 |
> enabled for me. |
| 8 |
> |
| 9 |
> I figured out how to solve my problem with DomU. I've changed tsc_mode |
| 10 |
> to something different from 0 or 4 and it seems started to work for |
| 11 |
> me. |
| 12 |
> |
| 13 |
> Here is short tsc_mode option description from sample VM config file: |
| 14 |
> |
| 15 |
> |
| 16 |
#---------------------------------------------------------------------------- |
| 17 |
> # tsc_mode : TSC mode (0=default, 1=native TSC, 2=never emulate, |
| 18 |
3=pvrdtscp) |
| 19 |
> # emulate TSC provides synced TSC for all vcpus, but lose perfomrance. |
| 20 |
> # native TSC leverages hardware's TSC(no perf loss), but vcpu's TSC may |
| 21 |
lose |
| 22 |
> # sync due to hardware's unreliable/unsynced TSC between CPUs. |
| 23 |
> # default intelligently uses native TSC on machines where it is safe, |
| 24 |
but |
| 25 |
> # switches to emulated if necessary after save/restore/migration |
| 26 |
> # pvrdtscp is for intelligent apps that use special Xen-only |
| 27 |
paravirtualized |
| 28 |
> # cpuid instructions to obtain offset/scaling/migration info and |
| 29 |
maximize |
| 30 |
> # performance within pools of machines that support the rdtscp |
| 31 |
instruction |
| 32 |
> tsc_mode=1 |
| 33 |
> |
| 34 |
|
| 35 |
Ah, glad to hear that. |
| 36 |
|
| 37 |
> BTW, does anybody has NTP server on a virtual machine? ;) |
| 38 |
> |
| 39 |
|
| 40 |
Actually, I do. With tickless, the clock drifts around unpredictably, so I |
| 41 |
resort to having one of my VMs sync to the NTP pool, while other VMs sync |
| 42 |
to that VM. |
| 43 |
|
| 44 |
Rgds, |
Archives