[PATCH v4 2/3] util: Add virHostCPUGetHaltPollTime

[Yang Fei]

On 2021/7/27 16:31, Michal Prívozník wrote:
> On 7/22/21 10:05 AM, Yang Fei wrote:
>> Add helper function virHostCPUGetHaltPollTime to obtain halt polling
>> time. If the kernel support halt polling time statistic, and mount
>> debugfs. This function will take effect on KVM VMs.
>>
>> Signed-off-by: Yang Fei <yangfei85 at huawei.com>
>> ---
>>  src/libvirt_private.syms |  1 +
>>  src/util/virhostcpu.c    | 39 +++++++++++++++++++++++++++++++++++++++
>>  src/util/virhostcpu.h    |  4 ++++
>>  3 files changed, 44 insertions(+)
>>
> 
>> diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
>> index bf7fda23af..7f577c3e3e 100644
>> --- a/src/util/virhostcpu.c
>> +++ b/src/util/virhostcpu.c
>> @@ -1535,3 +1535,42 @@ virHostCPUGetSignature(char **signature)
>>  }
>>  
>>  #endif /* __linux__ */
>> +
>> +int
>> +virHostCPUGetHaltPollTime(pid_t pid,
>> +                      unsigned long long *haltPollSuccess,
>> +                      unsigned long long *haltPollFail)
>> +{
>> +    g_autofree char *pidToStr = NULL;
>> +    g_autofree char *debugFsPath = NULL;
>> +    g_autofree char *kvmPath = NULL;
>> +    struct dirent *ent = NULL;
>> +    g_autoptr(DIR) dir = NULL;
>> +    bool found = false;
>> +
>> +    if (!(debugFsPath = virFileFindMountPoint("debugfs")))
>> +        return -1;
>> +
>> +    kvmPath = g_strdup_printf("%s/%s", debugFsPath, "kvm");
>> +    if (virDirOpenQuiet(&dir, kvmPath) != 1)
>> +        return -1;
>> +
>> +    pidToStr = g_strdup_printf("%lld%c", (long long)pid, '-');
> 
> Just a tiny nit: this could be "%lld-".
> 

Thanks for your review Michal. And do I need to send another version to fix it now?

>> +    while (virDirRead(dir, &ent, NULL) > 0) {
>> +        if (STRPREFIX(ent->d_name, pidToStr)) {
>> +            found = true;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!found)
>> +        return -1;
>> +
>> +    if (virFileReadValueUllongQuiet(haltPollSuccess, "%s/%s/%s", kvmPath,
>> +                                    ent->d_name, "halt_poll_success_ns") < 0 ||
>> +        virFileReadValueUllongQuiet(haltPollFail, "%s/%s/%s", kvmPath,
>> +                                    ent->d_name, "halt_poll_fail_ns") < 0)
>> +        return -1;
>> +
>> +    return 0;
>> +}
> 
> Michal
> 
> .
> 
Thanks,
Fei.