[dpdk-dev] The use of --log-level and its default state

[Wiles, Keith]

On 6/5/15, 8:58 AM, "Thomas Monjalon" <thomas.monjalon at 6wind.com> wrote:

>Keith, your mail is very long but it's maybe on purpose to show that
>there are too many logs ;)

Yes it was kind of the point, but only because I wanted to show the
complete output.
>
>2015-06-05 12:32, Wiles, Keith:
>> On 6/5/15, 5:00 AM, "Thomas Monjalon" <thomas.monjalon at 6wind.com> wrote:
>> >2015-05-27 15:10, Wiles, Keith:
>> >> I would like to have the log-level default changed to not log
>> >>everything,
>> >> but the user needs to enable the log messages if he needs to see more
>> >> information. Normally applications or systems are not so verbose,
>>but if
>> >> needed the user enables the verbose or debug messages.
>> >> 
>> >> Can we change the default logs and messages to be non-verbose
>>instead?
>> >
>> >Do you mean changing this line?
>> >    /* default value from build option */
>> >    internal_cfg->log_level = RTE_LOG_LEVEL;
>> >It means using the most verbose level available in the build.
>> >
>> >Maybe we should set RTE_LOG_NOTICE or RTE_LOG_WARNING,
>> >However, there is already --log-level for the user and
>>rte_set_log_level()
>> >for the application developper.
>> >So this default log level is only used for DPDK trials and development.
>> >Probably that being verbose is a good option for such cases?
>> >
>> The normal operation for most systems is no-news-is-good-news, meaning
>> only report warnings and errors if someone wants informational output it
>> should be enabled by the user. It seems PMDs and other parts of DPDK
>>print
>> out information which is not a warning or error, but are debug or
>> informational messages that are not very useful. The debug information
>>is
>> more for the developer then a user or even a developer of DPDK as the
>> debug information has nothing to do with the current developers goals.
>
>This assumption is not fully true.
>In normal applications DPDK doesn't show so many logs.
>But in testpmd or examples, the log level is not set (by default) and they
>behave as debug applications, which is probably a good default.
>However, as you say below, the log level of some messages is not well
>tuned.

The output was from Pktgen and I did not set any log-level in the app. I
would get the messages about non-vector and vector support when the port
is stopped/started. :-(
>
>> We can change the RTE_LOG_LEVEL to a value that only prints warning and
>> errors should always be printed. We can leave it or we can make that one
>> change to reduce the amount of clutter on the screen. Some of the PMD
>> information is printed out anytime the state changes, which effects the
>> application screen output.
>> 
>> When I have to interact with users of DPDK they sometimes miss critical
>> details in the output because of the sheer amount of output on the
>>screen.
>> Even most OSes try to output information to the screen is a sane way to
>> allow someone to quickly spot a problem.
>> 
>> Here is a normal output with log level at the default:
>> 
>[...] 
>> When I quit the application I get the four above are they really useful,
>> not really IMO. The PMD information and the EAL information is not very
>> use 99% of the time.
>
>Yes it is a debug mode.
>
>> Next is ‹log-level=0 on the command line.
>> 
>> EAL: Detected lcore 0 as core 0 on socket 0
>> EAL: Detected lcore 1 as core 1 on socket 0
>> EAL: Detected lcore 2 as core 2 on socket 0
>> EAL: Detected lcore 3 as core 3 on socket 0
>> EAL: Detected lcore 4 as core 4 on socket 0
>> EAL: Detected lcore 5 as core 8 on socket 0
>> EAL: Detected lcore 6 as core 9 on socket 0
>> EAL: Detected lcore 7 as core 10 on socket 0
>> EAL: Detected lcore 8 as core 11 on socket 0
>> EAL: Detected lcore 9 as core 16 on socket 0
>> EAL: Detected lcore 10 as core 17 on socket 0
>> EAL: Detected lcore 11 as core 18 on socket 0
>> EAL: Detected lcore 12 as core 19 on socket 0
>> EAL: Detected lcore 13 as core 20 on socket 0
>> EAL: Detected lcore 14 as core 24 on socket 0
>> EAL: Detected lcore 15 as core 25 on socket 0
>> EAL: Detected lcore 16 as core 26 on socket 0
>> EAL: Detected lcore 17 as core 27 on socket 0
>> EAL: Detected lcore 18 as core 0 on socket 1
>> EAL: Detected lcore 19 as core 1 on socket 1
>> EAL: Detected lcore 20 as core 2 on socket 1
>> EAL: Detected lcore 21 as core 3 on socket 1
>> EAL: Detected lcore 22 as core 4 on socket 1
>> EAL: Detected lcore 23 as core 8 on socket 1
>> EAL: Detected lcore 24 as core 9 on socket 1
>> EAL: Detected lcore 25 as core 10 on socket 1
>> EAL: Detected lcore 26 as core 11 on socket 1
>> EAL: Detected lcore 27 as core 16 on socket 1
>> EAL: Detected lcore 28 as core 17 on socket 1
>> EAL: Detected lcore 29 as core 18 on socket 1
>> EAL: Detected lcore 30 as core 19 on socket 1
>> EAL: Detected lcore 31 as core 20 on socket 1
>> EAL: Detected lcore 32 as core 24 on socket 1
>> EAL: Detected lcore 33 as core 25 on socket 1
>> EAL: Detected lcore 34 as core 26 on socket 1
>> EAL: Detected lcore 35 as core 27 on socket 1
>> EAL: Detected lcore 36 as core 0 on socket 0
>> EAL: Detected lcore 37 as core 1 on socket 0
>> EAL: Detected lcore 38 as core 2 on socket 0
>> EAL: Detected lcore 39 as core 3 on socket 0
>> EAL: Detected lcore 40 as core 4 on socket 0
>> EAL: Detected lcore 41 as core 8 on socket 0
>> EAL: Detected lcore 42 as core 9 on socket 0
>> EAL: Detected lcore 43 as core 10 on socket 0
>> EAL: Detected lcore 44 as core 11 on socket 0
>> EAL: Detected lcore 45 as core 16 on socket 0
>> EAL: Detected lcore 46 as core 17 on socket 0
>> EAL: Detected lcore 47 as core 18 on socket 0
>> EAL: Detected lcore 48 as core 19 on socket 0
>> EAL: Detected lcore 49 as core 20 on socket 0
>> EAL: Detected lcore 50 as core 24 on socket 0
>> EAL: Detected lcore 51 as core 25 on socket 0
>> EAL: Detected lcore 52 as core 26 on socket 0
>> EAL: Detected lcore 53 as core 27 on socket 0
>> EAL: Detected lcore 54 as core 0 on socket 1
>> EAL: Detected lcore 55 as core 1 on socket 1
>> EAL: Detected lcore 56 as core 2 on socket 1
>> EAL: Detected lcore 57 as core 3 on socket 1
>> EAL: Detected lcore 58 as core 4 on socket 1
>> EAL: Detected lcore 59 as core 8 on socket 1
>> EAL: Detected lcore 60 as core 9 on socket 1
>> EAL: Detected lcore 61 as core 10 on socket 1
>> EAL: Detected lcore 62 as core 11 on socket 1
>> EAL: Detected lcore 63 as core 16 on socket 1
>> EAL: Detected lcore 64 as core 17 on socket 1
>> EAL: Detected lcore 65 as core 18 on socket 1
>> EAL: Detected lcore 66 as core 19 on socket 1
>> EAL: Detected lcore 67 as core 20 on socket 1
>> EAL: Detected lcore 68 as core 24 on socket 1
>> EAL: Detected lcore 69 as core 25 on socket 1
>> EAL: Detected lcore 70 as core 26 on socket 1
>> EAL: Detected lcore 71 as core 27 on socket 1
>> EAL: Support maximum 128 logical core(s) by configuration.
>> EAL: Detected 72 lcore(s)
>> EAL: Auto-detected process type: PRIMARY
>> 
>> 
>> I suggest only the last three line are even remotely useful and we do
>>not
>> even print out the DPDK version number. I would put these as information
>> data and the EAL: does not need to be present and you can not turn that
>> information off.
>
>Yes, please fix the log level of the early messages.
>Why do you want to remove the EAL prefix?

I mean the last three lines are converted into the information below. Not
to remove all of the EAL: the others should remain.

>
>> Example output: (Email my wrap the lines below)
>> 
>> *** DPDK version 2.1.0 Copyright(c) 2010-2015 Intel Corporation. All
>> rights reserved. ***
>>   Detected 72 lcore(s) with supporting maximum 128 logical core(s) by
>> configuration
>>   Auto-detected process type: PRIMARY
>> 
>> Maybe print out the amount of memory configured and ports detected or
>> devices.
>
>These are info messages.
>
>> One of the license statements it to output the copyright notice for
>>binary
>> distributions and it would be nice to just output them anyway even in
>> source code form as they would need to do it anyway. We may need to add
>>a
>> couple more copyright notices as well here.
>
>Not sure that licences and copyrights should be printed.
>
>> Anyway let me know what you want to do here and I can try to produce a
>> patch.
>
>You may start by trying to remove early debug logs when level is higher.
>Thanks

Ok, will do.
Thanks
>