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

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 16:45 +0100 on 18 Jun (1245343507), Dan Magenheimer wrote:
> >       gdprintk(XENLOG_INFO, "Loaded VM expects a %"PRIu32"MHz TSC "
> >                "but CPU is %ldMHz; enabling RDTSC exiting.\n",
> >                hdr->gtsc_khz / 1000, cpu_khz / 1000); 
> 
> RDTSC "exiting"?  Do you mean RDTSC emulation?

Meh.  "RDTSC exiting" is Intel's term for it in the SDMs.

> Also, frankly, given the potential performance ramifications, perhaps
> this should be higher than XENLOG_INFO?

Not if it's going to print that out every time I migrate a VM.  This
whole feature is something I'd turn off anyway.

Cheers,

Tim.

> > -----Original Message-----
> > From: Zhang, Xiantao [mailto:xiantao.zhang@xxxxxxxxx]
> > Sent: Thursday, June 18, 2009 3:47 AM
> > To: Tim Deegan; Patrick Colp
> > Cc: Keir@xxxxxxxxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx; Fraser
> > Subject: RE: [Xen-devel] [PATCH] TSC scaling for live 
> > migration between
> > platforms with different TSC frequecies
> > 
> > 
> > Tim Deegan wrote:
> > > At 10:10 +0100 on 18 Jun (1245319857), Patrick Colp wrote:
> > >>> +        printk("Migrate to a platform with different 
> > freq:%ldMhz, "
> > >>> +            "expected freq:%dMhz, enable rdtsc exiting!\n",
> > >>> +                    cpu_khz / 1000, hdr->gtsc_khz / 1000);
> > >> 
> > >> Being pedantic, this should probably be:
> > >> 
> > >>      printk("Migrate to a platform with different freq: %ldMHz, "
> > >>             "expected freq: %dMHz, enable rdtsc exiting!\n",
> > >>              cpu_khz / 1000, hdr->gtsc_khz / 1000);
> > > 
> > > Being _pedantic_, it should be
> > > 
> > >       gdprintk(XENLOG_INFO, "Loaded VM expects a %"PRIu32"MHz TSC "
> > >                "but CPU is %ldMHz; enabling RDTSC exiting.\n",
> > >                hdr->gtsc_khz / 1000, cpu_khz / 1000); 
> > 
> > It maybe wonderful to add VM info (eg. Domain id) as Jan says 
> > in another mail. Thanks for your suggestions! I will change 
> > it in the final version!  :-)
> > Xiantao
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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