[libvirt] [PATCHv2 1/4] util: Introduce monitor capability interface

[Ján Tomko]

On Tue, Sep 18, 2018 at 03:38:44PM -0400, John Ferlan wrote:
>On 09/14/2018 09:30 PM, Wang Huaqiang wrote:
>> This patch introduces the resource monitor and creates the interface
>> for getting host capability of resource monitor from the system resource
>> control file system.
>>
>> The resource monitor take the role of RDT monitoring group, could be
>
>*takes...
>
>s/, could/ and could/
>
>> used to monitor the resource consumption information, such as the last
>> level cache occupancy and the utilization of memory bandwidth.
>>
>> Signed-off-by: Wang Huaqiang <huaqiang.wang at intel.com>
>> ---
>>  src/util/virresctrl.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 124 insertions(+)
>>

[...]

>> +
>> +    rv = virFileReadValueUint(&info_monitor->max_monitor,
>> +                              SYSFS_RESCTRL_PATH "/info/L3_MON/num_rmids");
>> +    if (rv == -2) {
>> +        /* The file doesn't exist, so it's unusable for us, probably resource
>> +         * monitor unsupported */
>> +        VIR_INFO("The path '" SYSFS_RESCTRL_PATH "/info/L3_MON/num_rmids' "
>> +                 "does not exist");
>
>Add virResetLastError()
>
>[avoids having this error in Last and something else failing and spewing
>the error]
>

The return value of -2 means no error was set, so there is nothing to do
here.

Also, virResetLastError is meant to be used before starting an API.
It only resets the thread-local error object (which can only contain one
error), it cannot possibly unlog an error that was logged earlier.
In that case, creating a Quiet version of the function is the proper
solution.

Jano

>> +        ret = 0;
>> +        goto cleanup;
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