Re: [PATCH v3 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

Hari Bathini
2016-12-13T18:47:44Z

Hi Eric,

On Monday 12 December 2016 11:57 PM, Eric W. Biederman wrote:
> Hari Bathini <hbathini@linux.vnet.ibm.com> writes:
>
>> With the advert of container technologies like docker, that depend
>> on namespaces for isolation, there is a need for tracing support for
>> namespaces. This patch introduces new PERF_RECORD_NAMESPACES event
>> for tracing based on namespaces related info.
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index c66a485..2a48fc6 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -344,7 +344,8 @@ struct perf_event_attr {
>> use_clockid : 1, /* use @clockid for time fields */
>> context_switch : 1, /* context switch data */
>> write_backward : 1, /* Write ring buffer from end to beginning */
>> - __reserved_1 : 36;
>> + namespaces : 1, /* include namespaces data */
>> + __reserved_1 : 35;
>>
>> union {
>> __u32 wakeup_events; /* wakeup every n events */
>> @@ -610,6 +611,18 @@ struct perf_event_header {
>> __u16 size;
>> };
>>
>> +enum {
>> + NET_NS_INDEX = 0,
>> + UTS_NS_INDEX = 1,
>> + IPC_NS_INDEX = 2,
>> + PID_NS_INDEX = 3,
>> + USER_NS_INDEX = 4,
>> + MNT_NS_INDEX = 5,
>> + CGROUP_NS_INDEX = 6,
>> +
>> + NAMESPACES_MAX, /* maximum available namespaces */
>> +};
>> +
>> enum perf_event_type {
>>
>> /*
>> @@ -862,6 +875,18 @@ enum perf_event_type {
>> */
>> PERF_RECORD_SWITCH_CPU_WIDE = 15,
>>
>> + /*
>> + * struct {
>> + * struct perf_event_header header;
>> + *
>> + * u32 pid, tid;
>> + * u64 dev_num;
>> + * u64 inode_num[NAMESPACES_MAX];
> There needs to be one device number per inode. While it is true that
> today the device number is always the same. That is not necessarily so.
> I reserve the right to have the device number vary per namespace
> so that I don't need to implement a namespace of namespaces.
>
> These are st_dev and st_ino of the inode for the namespace.

Do you mean..

st_dev = encode_dev(inode->i_sb->s_dev); ?
st_ino = inode->i_ino; ?

Thanks
Hari