Re: [PATCH 00/14] Present useful limits to user (v2)

On 07/15/16 14:19, Richard Weinberger wrote:

Hi!

Am 15.07.2016 um 12:35 schrieb Topi Miettinen:

quoted

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 don't know. What kind of changes do you think would be needed?

-Topi

Thanks,
//richard

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