linux-toradex.git/Documentation/accounting, branch v5.0-rc7

psi: cgroup support

2018-10-26T23:26:32+00:00

On a system that executes multiple cgrouped jobs and independent
workloads, we don't just care about the health of the overall system, but
also that of individual jobs, so that we can ensure individual job health,
fairness between jobs, or prioritize some jobs over others.

This patch implements pressure stall tracking for cgroups.  In kernels
with CONFIG_PSI=y, cgroup2 groups will have cpu.pressure, memory.pressure,
and io.pressure files that track aggregate pressure stall times for only
the tasks inside the cgroup.

Link: http://lkml.kernel.org/r/20180828172258.3185-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner 
Acked-by: Tejun Heo 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Daniel Drake 
Tested-by: Suren Baghdasaryan 
Cc: Christopher Lameter 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Cc: Mike Galbraith 
Cc: Peter Enderborg 
Cc: Randy Dunlap 
Cc: Shakeel Butt 
Cc: Vinayak Menon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

psi: pressure stall information for CPU, memory, and IO

2018-10-26T23:26:32+00:00

When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills.  In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.

In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.

A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively.  Stall states are aggregate versions of the per-task delay
accounting delays:

       cpu: some tasks are runnable but not executing on a CPU
       memory: tasks are reclaiming, or waiting for swapin or thrashing cache
       io: tasks are waiting for io completions

These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit.  They can also indicate when the system
is approaching lockup scenarios and OOMs.

To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states.  Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime.  A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).

[hannes@cmpxchg.org: doc fixlet, per Randy]
  Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
  Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
  Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
  Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Daniel Drake 
Tested-by: Suren Baghdasaryan 
Cc: Christopher Lameter 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Cc: Mike Galbraith 
Cc: Peter Enderborg 
Cc: Randy Dunlap 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Cc: Vinayak Menon 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

tools: move accounting tool from Documentation

2016-09-23T19:07:15+00:00

Move accounting tool to tools and remove it from Documentation
Makefile. Update location information for this tool. Create a
new Makefile to build accounting. It can be built from top level
directory or from accounting directory:

Run make -C tools/accounting or cd tools/accounting; make

Acked-by: Jonathan Corbet 
Signed-off-by: Shuah Khan

taskstats: fix nl parsing in accounting/getdelays.c

2016-04-27T16:50:14+00:00

The type TASKSTATS_TYPE_NULL should always be ignored.

When jumping to the next attribute, only the length of the current
attribute should be added, not the length of all nested attributes.
This last bug was not visible before commit 80df554275c2, because the
kernel didn't put more than two nested attributes.

Fixes: a3baf649ca9c ("[PATCH] per-task-delay-accounting: documentation")
Fixes: 80df554275c2 ("taskstats: use the libnl API to align nlattr on 64-bit")
Signed-off-by: Nicolas Dichtel 
Signed-off-by: David S. Miller

Documentation-getdelays: Apply a recommendation from "checkpatch.pl" in main()

2015-12-24T14:22:32+00:00

The script "checkpatch.pl" pointed out that assignments should usually
not be performed within condition checks.
Thus move the assignment for the variable "nl_sd" to a separate statement.

Signed-off-by: Markus Elfring 
Signed-off-by: Jonathan Corbet

Documentation: use subdir-y to avoid unnecessary built-in.o files

2014-09-26T09:02:55+00:00

Change the Documentation makefiles from obj-m to subdir-y
to avoid generating unnecessary built-in.o files since nothing
in Documentation/ is ever linked in to vmlinux.

Signed-off-by: Peter Foley 
Acked-by: Sam Ravnborg 
Signed-off-by: Randy Dunlap 
Signed-off-by: Jiri Kosina

Documentation/accounting/getdelays.c: add missing null-terminate after strncpy call

2014-06-23T23:47:44+00:00

Added a guaranteed null-terminate after call to strncpy.

This was partly found using a static code analysis program called
cppcheck.

Signed-off-by: Rickard Strandqvist 
Acked-by: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/accounting/getdelays.c: avoid strncpy in accounting tool

2013-07-03T23:08:06+00:00

Avoid strncpy anti-pattern.

[akpm@linux-foundation.org: remove the str[cpy|dup] altogether]
Signed-off-by: Kees Cook 
Cc: Andreas Schwab 
Cc: Rob Landley 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

doc: Remove unnecessary declarations from Documentation/accounting/getdelays.c

2012-11-26T13:22:21+00:00

stime and utime are declared __u64 but are never used.  On a glibc system
this is harmless lint, but on a uClibc system, because of the difference
in they way header files stack, including stdio.h brings in time.h and
this causes a name collision with stime.  Since these are useless anyhow,
we remove them.

Signed-off-by: Anthony G. Basile 
Signed-off-by: Jiri Kosina

doc: getdelays.c: remember to close() socket on error in create_nl_socket()

2012-09-01T16:58:59+00:00

If the call to setsockopt() fails in
Documentation/accounting/getdelays.c::create_nl_socket() we return -1
without closing the socket, thus leaking it when the 'fd' variable
goes out of scope.

Easily fixed by just jumping to the 'error' label instead of returning
since we do the proper cleanup there.

While I was there I noticed that the error message that is printet if
setsockopt() fails was broken over two lines - put that on a single
line so it is easier to grep for.

Signed-off-by: Jesper Juhl 
Signed-off-by: Jiri Kosina