On 12/22/2020 2:22 AM, Hideyuki Yamashita wrote:
Hello,
Thanks for your comments.
Please see my comments inline tagged with [HY].
04/12/2020 08:51, Hideyuki Yamashita:
In general, DPDK application consumes CPU usage because it polls
incoming packets using rx_burst API in infinite loop.
This makes difficult to estimate how much CPU usage is really
used to send/receive packets by the DPDK application.
For example, even if no incoming packets arriving, CPU usage
looks nearly 100% when observed by top command.
It is beneficial if developers can observe real CPU usage of the
DPDK application.
Such information can be exported to monitoring application like
prometheus/graphana and shows CPU usage graphically.
To achieve above, this patch set provides apistats functionality.
apistats provides the followiing two counters for each lcore.
- rx_burst_counts[RTE_MAX_LCORE]
- tx_burst_counts[RTE_MAX_LCORE]
Those accumulates rx_burst/tx_burst counts since the application starts.
Please could you compare with what rte_jobstats offers?
http://code.dpdk.org/dpdk/latest/source/lib/librte_jobstats/rte_jobstats.h
I feel all of this shares the same goals as librte_power work.
[HY]
Thanks for your commetns.
You are correct. As you well know, l3fwd-power measures "how cpu cores
are busy".
And in that sense, the goal of my proposal is the same with yours .
Moreover l3fwd-power is more precise than my proposal.
Point of my proposal is
- more easy to use
- less code impact on application code
I think that if application developer wants to need to measure "how cpu
cores are busy" he/she will needs to implement
- logic similar with l3fwd-power
or
- use jobstats API
But it is rather heavy for existing applications.
By using my proposal, it is "much easier" to implement.
(But it is "rough" measurement. I think it is trade-off)
How do you think about the idea?
[...]
- basic API counting functionality(apistats) into librte_ethdev
Could it be it be accessible via rte_telemetry?
http://code.dpdk.org/dpdk/latest/source/lib/librte_telemetry/rte_telemetry.h
[HY]
OK.
Currently, no reason not using telemetry.
I think telemetry is useful for applications which does NOT call DPDK
API(C lang API) directly.
My patchset provide only C API to retrieve apistats.
But if assuming not all applications call C API, then I think it is
reasonable to add telemetry in addition to C API for exposing stats.
Do you think "exposure via C API" is not needed?
Hi Hideyuki,
With current implementation the change will cause a performance degradation for
all users, even if they use the stats or not.
Even if the statics update wrapped with #ifdef, as suggested, the functionality
is simple and it can be easily implemented by application using Rx/Tx callbacks,
again as suggested, without introducing this new complexity.
And for more complex usage, the jobstats already tries to provide a generic
library for it, or application specific needs can be implemented in application
level as done is l3fwd-power.
Overall I agree the problem this patch is trying to solve is a valid one, but
not sure about the current implementation, and I am marking current version as
'rejected', please feel free to send a new version with a new approach.
Thanks,
ferruh
