When running turbostat on a virtual machine the error
turbostat: msr 0 offset 0xe2 read failed: Input/output error
is output to the user.
/dev/msr and perf do not work on a virtual machine. turbostat is
dependent on that support so turbostat does not work either.
A common way of determining if the system is a virtual machine is to
search /proc/cpuinfo flags entry for "hypervisor". turbostat must output
a proper error message when found.
Signed-off-by: Prarit Bhargava <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Len Brown <[email protected]>
---
tools/power/x86/turbostat/turbostat.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 0dafba2c1e7d..ca1ea68bc4e8 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -5088,6 +5088,34 @@ void cmdline(int argc, char **argv)
}
}
+int has_hypervisor(void)
+{
+ FILE *cpuinfo;
+ char *flags, *hypervisor;
+ char *buffer;
+
+ /* On VMs /proc/cpuinfo contains a "flags" entry for hypervisor */
+ cpuinfo = fopen_or_die("/proc/cpuinfo", "ro");
+
+ buffer = malloc(4096);
+ if (!buffer)
+ err(-ENOMEM, "buffer malloc fail");
+
+ fread(buffer, 1024, 1, cpuinfo);
+
+ flags = strstr(buffer, "flags");
+ rewind(cpuinfo);
+ fseek(cpuinfo, flags - buffer, SEEK_SET);
+ fgets(buffer, 4096, cpuinfo);
+ fclose(cpuinfo);
+
+ hypervisor = strstr(buffer, "hypervisor");
+
+ free(buffer);
+
+ return !!hypervisor;
+}
+
int main(int argc, char **argv)
{
outf = stderr;
@@ -5097,6 +5125,12 @@ int main(int argc, char **argv)
if (!quiet)
print_version();
+ if (has_hypervisor()) {
+ fprintf(outf,
+ "turbostat is not supported on virtual machines.\n");
+ return -ENXIO;
+ }
+
probe_sysfs();
turbostat_init();
--
1.8.5.5
On Tue, 25 Jul 2017, Prarit Bhargava wrote:
> A common way of determining if the system is a virtual machine is to
> search /proc/cpuinfo flags entry for "hypervisor". turbostat must output
> a proper error message when found.
Maybe you could output that message only if it fails to both use
/dev/msr and perf *and* it is under a virtual machine? That would have
better forward compatibility, maybe someday /dev/msr or perf will work
inside a VM for what turbostat needs...
--
Henrique Holschuh
Henrique,
I like your suggestion, thanks!
BTW. let's discuss (and patch) turbostat on linux-pm, rather than on lkml.
thanks,
-Len
On Tue, Jul 25, 2017 at 11:59 AM, Henrique de Moraes Holschuh
<[email protected]> wrote:
> On Tue, 25 Jul 2017, Prarit Bhargava wrote:
>> A common way of determining if the system is a virtual machine is to
>> search /proc/cpuinfo flags entry for "hypervisor". turbostat must output
>> a proper error message when found.
>
> Maybe you could output that message only if it fails to both use
> /dev/msr and perf *and* it is under a virtual machine? That would have
> better forward compatibility, maybe someday /dev/msr or perf will work
> inside a VM for what turbostat needs...
>
> --
> Henrique Holschuh
--
Len Brown, Intel Open Source Technology Center
On 07/26/2017 11:09 PM, Len Brown wrote:
> Henrique,
>
> I like your suggestion, thanks!
>
> BTW. let's discuss (and patch) turbostat on linux-pm, rather than on lkml.
Sure -- Len, can you add an entry to RHMAINTAINERS for that? I use the
get_maintainer.pl script to apply all cc's.
P.
On 07/26/2017 11:09 PM, Len Brown wrote:
> Henrique,
>
> I like your suggestion, thanks!
>
> BTW. let's discuss (and patch) turbostat on linux-pm, rather than on lkml.
>
> thanks,
> -Len
>
>
> On Tue, Jul 25, 2017 at 11:59 AM, Henrique de Moraes Holschuh
> <[email protected]> wrote:
>> On Tue, 25 Jul 2017, Prarit Bhargava wrote:
>>> A common way of determining if the system is a virtual machine is to
>>> search /proc/cpuinfo flags entry for "hypervisor". turbostat must output
>>> a proper error message when found.
>>
>> Maybe you could output that message only if it fails to both use
>> /dev/msr and perf *and* it is under a virtual machine? That would have
>> better forward compatibility, maybe someday /dev/msr or perf will work
>> inside a VM for what turbostat needs...
To answer Len's previous question: I was wrong in my description. perf does
work (mostly) under virt. So this would only be for the msr code. I'll post a
v2 to linux-pm, and take Henrique's suggestion to only trigger on an msr read
failure.
P.
>>
>> --
>> Henrique Holschuh
>
>
>
> Len, can you add an entry to RHMAINTAINERS for that?
done.
thx.
Len