[PATCH v2 00/14] perf, persistent: Kernel updates for perf tool integration

[Robert Richter <rric@kernel.org>]

This patch set implements out of the box support of perf tools for
persistent events. For this the kernel must provide necessary
information about existing persistent events via sysfs to userland.
Persistent events are provided by the kernel with readonly event
buffers. To allow the independent usage of the event buffers by any
process without limiting other processes, multiple users of a single
event must be handled too.

The basic concept is to use a pmu as an event container for persistent
events. The pmu registers events in sysfs and provides format and
event information for the userland. The persistent event framework
requires to add events to the pmu dynamically.

With the information in sysfs userland knows about how to setup the
perf_event attribute of a persistent event. Since a persistent event
always has the persistent flag set, a way is needed to express this in
sysfs. A new syntax is used for this. With 'attr<num>:<mask>' any bit
in the attribute structure may be set in a similar way as using
'config<num>', but <num> is an index that points to the u64 value to
change within the attribute.

For persistent events the persistent flag (bit 23 of flag field in
struct perf_event_attr) needs to be set which is expressed in sysfs
with "attr5:23". E.g. the mce_record event is described in sysfs as
follows:

 /sys/bus/event_source/devices/persistent/events/mce_record:persistent,config=106
 /sys/bus/event_source/devices/persistent/format/persistent:attr5:23

Note that perf tools need to support the 'attr<num>' syntax that is
added in a separate patch set. With it we are able to run perf tool
commands to read persistent events, e.g.:

 # perf record -e persistent/mce_record/ sleep 10
 # perf top -e persistent/mce_record/

In general the new syntax is flexible to describe with sysfs any event
to be setup by perf tools.

First patches contain also fixes and reworks made after reviewing
code. Could be applied separately.

Patches base on Boris' patches which I have rebased to latest
tip/perf/core. All patches can be found here:

 git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile.git persistent-v2

I wonder if this patch set could be applied to a tip/perf topic
branch? This would avoid reposting already reviewed patches.

Note: The perf tools patch set do not need to be reposted.

-Robert


Changes for V2:
* Merged minor changes into Boris' patches
* Included Boris' patches for review
* Document attr<index> syntax in sysfs ABI
* Adding cpu check to perf_get_persistent_event_fd()
* Rebased to latest tip/perf/core


Borislav Petkov (4):
  perf, ring_buffer: Use same prefix
  perf: Add persistent events
  perf: Add persistent event facilities
  MCE: Enable persistent event

Robert Richter (10):
  perf, persistent: Rework struct pers_event_desc
  perf, persistent: Remove rb_put()
  perf, persistent: Introduce get_persistent_event()
  perf, persistent: Reworking perf_get_persistent_event_fd()
  perf, persistent: Protect event lists with mutex
  perf, persistent: Avoid adding identical events
  perf, persistent: Implementing a persistent pmu
  perf, persistent: Name each persistent event
  perf, persistent: Exposing persistent events using sysfs
  perf, persistent: Allow multiple users for an event

 .../testing/sysfs-bus-event_source-devices-format  |  43 ++-
 arch/x86/kernel/cpu/mcheck/mce.c                   |  19 ++
 include/linux/perf_event.h                         |   9 +-
 include/uapi/linux/perf_event.h                    |   3 +-
 kernel/events/Makefile                             |   2 +-
 kernel/events/core.c                               |  56 ++--
 kernel/events/internal.h                           |   3 +
 kernel/events/persistent.c                         | 320 +++++++++++++++++++++
 kernel/events/ring_buffer.c                        |   7 +-
 9 files changed, 419 insertions(+), 43 deletions(-)
 create mode 100644 kernel/events/persistent.c

-- 
1.8.1.1