On 13.09.2012 14:42, Gleb Natapov wrote:
On Thu, Sep 13, 2012 at 02:05:23PM +0200, Peter Lieven wrote:
On 13.09.2012 10:05, Gleb Natapov wrote:
On Thu, Sep 13, 2012 at 10:00:26AM +0200, Paolo Bonzini wrote:
Il 13/09/2012 09:57, Gleb Natapov ha scritto:
#rdmsr -0 0x194
0000000000011100
#rdmsr -0 0xce
00000c0004011103
Yes, that can help implementing it in KVM. But without a spec to
understand what the bits actually mean, it's just as risky...
Peter, do you have any idea where to get the spec of the memory
controller MSRs in Nehalem and newer processors? Apparently, memtest is
using them (and in particular 0x194) to find the speed of the FSB, or
something like that.
Why would anyone will want to run memtest in a vm? May be just add those
MSRs to ignore list and that's it.
>From the output it looks like it's basically a list of bits. Returning
something sensible is better, same as for the speed scaling MSRs.
Everything is list of bits in computers :) At least 0xce is documented in SDM.
It cannot be implemented in a migration safe manner.
What do you suggest just say memtest does not work?
Why do you want to run it in a guest?
Testing memory thorughput of different host memory layouts/settings
(hugepages, ksm etc.).
Stress testing new settings and qemu-kvm builds.
Testing new nodes with a VM which claims all available pages. Its a lot
easier than booting
a node with a CD and attaching to the Console.
This, of course, is all not missing critical and call also be done with
cpu model qemu64. I just
came across memtest no longer working and where wondering if there is a
general regressing.
BTW, from
http://opensource.apple.com/source/xnu/xnu-1228.15.4/osfmk/i386/tsc.c?txt
#define MSR_FLEX_RATIO 0x194
#define MSR_PLATFORM_INFO 0x0ce
#define BASE_NHM_CLOCK_SOURCE 133333333ULL
#define CPUID_MODEL_NEHALEM 26
switch (cpuid_info()->cpuid_model) {
case CPUID_MODEL_NEHALEM: {
uint64_t cpu_mhz;
uint64_t msr_flex_ratio;
uint64_t msr_platform_info;
/* See if FLEX_RATIO is being used */
msr_flex_ratio = rdmsr64(MSR_FLEX_RATIO);
msr_platform_info = rdmsr64(MSR_PLATFORM_INFO);
flex_ratio_min = (uint32_t)bitfield(msr_platform_info, 47, 40);
flex_ratio_max = (uint32_t)bitfield(msr_platform_info, 15, 8);
/* No BIOS-programed flex ratio. Use hardware max as default */
tscGranularity = flex_ratio_max;
if (msr_flex_ratio & bit(16)) {
/* Flex Enabled: Use this MSR if less than max */
flex_ratio = (uint32_t)bitfield(msr_flex_ratio, 15, 8);
if (flex_ratio < flex_ratio_max)
tscGranularity = flex_ratio;
}
/* If EFI isn't configured correctly, use a constant
* value. See 6036811.
*/
if (busFreq == 0)
busFreq = BASE_NHM_CLOCK_SOURCE;
cpu_mhz = tscGranularity * BASE_NHM_CLOCK_SOURCE;
kprintf("[NHM] Maximum Non-Turbo Ratio = [%d]\n",
(uint32_t)tscGranularity);
kprintf("[NHM] CPU: Frequency = %6d.%04dMhz\n",
(uint32_t)(cpu_mhz / Mega), (uint32_t)(cpu_mhz % Mega));
break;
}
Peter
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