libcontainer/intelrdt: remove 'omitempty' property from CMT and MBM counters

[xiaochenshen]

If the values of CMT and MBM counters are zero, they will be omitted as
empty items when getting Intel RDT stats.

Remove 'omitempty' property from CMT and MBM counters to display zero
values.

Signed-off-by: Xiaochen Shen xiaochen.shen@intel.com

[xiaochenshen]

@Creatone @kolyshkin @AkihiroSuda
Could you help review this PR? Thank you!

[kolyshkin]

LGTM

[xiaochenshen]

@AkihiroSuda @crosbymichael
@Creatone
Could you help review at your convenience? This is only a trivial fix.

[eero-t]

Doesn't e.g. BlkIo have the same problem?

[xiaochenshen]

Doesn't e.g. BlkIo have the same problem?

@eero-t From my understanding, it depends on the meaning of the value in the field. If the zero/nil/false value has special meaning and it should not be omitted, we'd better remove omitempty option. Please correct me if I am wrong.

From https://golang.org/pkg/encoding/json/:
The "omitempty" option specifies that the field should be omitted from the encoding if the field has an empty value, defined as false, 0, a nil pointer, a nil interface value, and any empty array, slice, map, or string.

[eero-t]

@xiaochenshen For example in types/events.go all fields have "omitempty":

type BlkioEntry struct {
        Major uint64 `json:"major,omitempty"`
        Minor uint64 `json:"minor,omitempty"`
        Op    string `json:"op,omitempty"`
        Value uint64 `json:"value,omitempty"`
}

type Blkio struct {
        IoServiceBytesRecursive []BlkioEntry `json:"ioServiceBytesRecursive,omitempty"`
        IoServicedRecursive     []BlkioEntry `json:"ioServicedRecursive,omitempty"`
        IoQueuedRecursive       []BlkioEntry `json:"ioQueueRecursive,omitempty"`
        IoServiceTimeRecursive  []BlkioEntry `json:"ioServiceTimeRecursive,omitempty"`
        IoWaitTimeRecursive     []BlkioEntry `json:"ioWaitTimeRecursive,omitempty"`
        IoMergedRecursive       []BlkioEntry `json:"ioMergedRecursive,omitempty"`
        IoTimeRecursive         []BlkioEntry `json:"ioTimeRecursive,omitempty"`
        SectorsRecursive        []BlkioEntry `json:"sectorsRecursive,omitempty"`
}

But it's common for minor for a device file to be zero.

Minor being omitted for some of the data output by events looks IMHO pretty odd, and I can't see any advantage on it, it just makes parsing the data from "events" command harder.

(I noticed this when testing my own code for some other device limits, as I had modeled that code after BlkIo.)

[xiaochenshen]

@eero-t
In my opinion, BlkIo has the same problem from your description.
Maybe you could open an issue or PR for further discussion?