Re: [PATCH v2] mem: telemetry support for memseg and element information

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, May 20, 2022 at 12:27:12AM +0530, Amit Prakash Shukla wrote:
> Changes adds telemetry support to display memory occupancy
> in memseg and the information of the elements allocated from
> a memseg based on arguments provided by user. This patch
> adds following endpoints:
> 
> 1. /eal/active_memseg_list
> The command displays the memseg list from which the memory
> has been allocated.
> Example:
> --> /eal/active_memseg_list
> {"/eal/active_memseg_list": [0, 1]}
> 
> 2. /eal/memseg_list,<memseg-list-id>
> The command outputs the memsegs, from which the memory is
> allocated, for the memseg_list given as input. Command also
> supports help.
> Example:
> --> /eal/memseg_list,help
> {"/eal/memseg_list": "/eal/memseg_list,<memseg-list-id>"}
> 
> --> /eal/memseg_list,1
> {"/eal/memseg_list": [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, \
>  12, 13, 14, 15]}
> 

This is really confusing because, if I understand this correctly,  we have
a conflict of terms here - in telemetry "list" is generally used to get the
possible values of ids at the top level, with the info and other commands
used to get the next level of detail down, while the initial command here
returns details on the memseg lists, i.e. it should really be
"memseg_list_list" command, i.e. list the memseg lists. Can we perhaps come
up with a different term for the memseg list, because right now I think the
above commands should be "memseg_list_list" and "memseg_list_info"?


> 3. /eal/memseg_info,<memseg-list-id>:<memseg-id>
> The command outputs the memseg information based on the
> memseg-list and the memseg-id given as input. Command also
> supports help.
> Example:
> --> /eal/memseg_info,help
> {"/eal/memseg_info": "/eal/memseg_info,<memseg-list-id>: \
> <memseg-id>"}
> 
> --> /eal/memseg_info,0:10
> {"/eal/memseg_info": {"Memseg_list_index": 0,  \
> "Memseg_index": 10, "Memseg_list_len": 64,     \
> "Start_addr": "0x260000000", "End_addr": "0x280000000",  \
> "Size": 536870912}}
> 
> --> /eal/memseg_info,1:15
> {"/eal/memseg_info": {"Memseg_list_index": 1,   \
> "Memseg_index": 15, "Memseg_list_len": 64,      \
> "Start_addr": "0xb20000000", "End_addr": "0xb40000000",  \
> "Size": 536870912}}
> 

For telemetry library, the parameters should all be comma-separated rather
than colon-separated.

> 4. /eal/elem_list,<heap-id>:<memseg-list-id>:<memseg-id>
> The command outputs number of elements in a memseg based
> on the heap-id, memseg-list-id and memseg-id given as input.
> Command also supports help.
> Example:
> --> /eal/elem_list,help
> {"/eal/elem_list": "/eal/elem_list,<heap-id>:  \
> <memseg-list-id>:<memseg-id>"}
> 
> --> /eal/elem_list,0:0:63
> {"/eal/elem_list": {"Element_count": 52}}
> 
> --> /eal/elem_list,0:1:15
> {"/eal/elem_list": {"Element_count": 52}}
> 
> 5. /eal/elem_info,<heap-id>:<memseg-list-id>:<memseg-id>:  \
>    <elem-start-id>-<elem-end-id>
> The command outputs element information like element start
> address, end address, to which memseg it belongs, element
> state, element size. User can give a range of elements to be
> printed. Command also supports help.
> Example:
> --> /eal/elem_info,help
> {"/eal/elem_info": "/eal/elem_info,<heap-id>:  \
> <memseg-list-id>:<memseg-id>: <elem-start-id>-<elem-end-id>"}
> 
> --> /eal/elem_info,0:1:15:1-2
> {"/eal/elem_info": {"elem_info.1": {"msl_id": 1,     \
> "ms_id": 15, "memseg_start_addr": "0xb20000000",     \
> "memseg_end_addr": "0xb40000000",                    \
> "element_start_addr": "0xb201fe680",                 \
> "element_end_addr": "0xb20bfe700",                   \
> "element_size": 10485888, "element_state": "Busy"},  \
> "elem_info.2": {"msl_id": 1, "ms_id": 15,            \
> "memseg_start_addr": "0xb20000000",                  \
> "memseg_end_addr": "0xb40000000",                    \
> "element_start_addr": "0xb20bfe700",                 \
> "element_end_addr": "0xb215fe780", "element_size": 10485888, \
> "element_state": "Busy"}, "Element_count": 2}}
> 

The "elem" name is ambiguous, I think. Are these malloc elements or some
other type of elements.


> Increased telemetry output buffer to 64K to support large
> size telemetry data output.
> 

That's a 4x increase in max size. Is it really necessary? Is telemetry the
best way to output this info, and do you see users really needing it?