On 7/15/2016 10:19 AM, Richard Weinberger wrote:
> Hi!
> 
> Am 15.07.2016 um 12:35 schrieb Topi Miettinen:
>> Hello,
>>
>> There are many basic ways to control processes, including capabilities,
>> cgroups and resource limits. However, there are far fewer ways to find out
>> useful values for the limits, except blind trial and error.
>>
>> This patch series attempts to fix that by giving at least a nice starting
>> point from the highwater mark values of the resources in question.
>> I looked where each limit is checked and added a call to update the mark
>> nearby.
>>
>> Example run of program from Documentation/accounting/getdelauys.c:
>>
>> ./getdelays -R -p `pidof smartd`
>> printing resource accounting
>> RLIMIT_CPU=0
>> RLIMIT_FSIZE=0
>> RLIMIT_DATA=18198528
>> RLIMIT_STACK=135168
>> RLIMIT_CORE=0
>> RLIMIT_RSS=0
>> RLIMIT_NPROC=1
>> RLIMIT_NOFILE=55
>> RLIMIT_MEMLOCK=0
>> RLIMIT_AS=130879488
>> RLIMIT_LOCKS=0
>> RLIMIT_SIGPENDING=0
>> RLIMIT_MSGQUEUE=0
>> RLIMIT_NICE=0
>> RLIMIT_RTPRIO=0
>> RLIMIT_RTTIME=0
>>
>> ./getdelays -R -C /sys/fs/cgroup/systemd/system.slice/smartd.service/
>> printing resource accounting
>> sleeping 1, blocked 0, running 0, stopped 0, uninterruptible 0
>> RLIMIT_CPU=0
>> RLIMIT_FSIZE=0
>> RLIMIT_DATA=18198528
>> RLIMIT_STACK=135168
>> RLIMIT_CORE=0
>> RLIMIT_RSS=0
>> RLIMIT_NPROC=1
>> RLIMIT_NOFILE=55
>> RLIMIT_MEMLOCK=0
>> RLIMIT_AS=130879488
>> RLIMIT_LOCKS=0
>> RLIMIT_SIGPENDING=0
>> RLIMIT_MSGQUEUE=0
>> RLIMIT_NICE=0
>> RLIMIT_RTPRIO=0
>> RLIMIT_RTTIME=0
>>
>> In this example, smartd is running as a non-root user. The presented
>> values can be used as a starting point for giving new limits to the
>> service.
> 
> I don't think it is worth sprinkling the kernel with update_resource_highwatermark()
> calls just to get these metrics.
> 
> Can't we teach the existing perf infrastructure to collect these highwatermarks for us?

I'm not sure about perf (I don't know the internals of perf well enough
to comment), but I'm sure the systemtap infrastructure could do this,
and a preconfigured systemtap script could be shipped with the package
that would allow this.


-- 
Doug Ledford <dledford@redhat.com>
    GPG Key ID: 0E572FDD