Re: [PATCH 1/2] Update perf_event ABI documentation: format andevents

From: Vince Weaver
Date: Fri Aug 23 2013 - 15:56:23 EST



It's been a month, are there any objections to these perf_event ABI
documentation updates?

Vince


On Thu, 25 Jul 2013, Vince Weaver wrote:

>
> This clarifies some of the ABI, as there has been some confusion
> and minor breakages lately. Most notably it documents that as of
> 3.10 the events entries can contain decimal values in addition to
> hex.
>
> This is version 2 containing whitespace fixes suggested by
> Jiri Olsa.
>
> Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> index 3c1cc24..16d9107 100644
> --- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> @@ -1,30 +1,52 @@
> -What: /sys/devices/cpu/events/
> +What: /sys/bus/event_source/devices/<dev>/events
> +
> +Date: 2013/01/08
> +
> +Contact: Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
> +
> +Description: Generic performance monitoring events
> +
> + A collection of performance monitoring events that are
> + supported by the PMU (performance monitoring unit)
> + specified by "<dev>". These events can be monitored
> + using the 'perf(1)' tool.
> +
> + The contents of each file is a list of attribute names
> + (as found in the corresponding
> + /sys/bus/event_source/devices/<dev>/format
> + file) separated by commas. Each entry has
> + an optional value (either hex or decimal). If no
> + value is specified than it is assumed to be a single-bit
> + field with a value of 1.
> +
> + An example of what you might find:
> + event=0x2,inv,ldlat=3
> +
> +
> +What: /sys/devices/cpu/events/branch-instructions
> /sys/devices/cpu/events/branch-misses
> - /sys/devices/cpu/events/cache-references
> + /sys/devices/cpu/events/bus-cycles
> /sys/devices/cpu/events/cache-misses
> - /sys/devices/cpu/events/stalled-cycles-frontend
> - /sys/devices/cpu/events/branch-instructions
> - /sys/devices/cpu/events/stalled-cycles-backend
> - /sys/devices/cpu/events/instructions
> + /sys/devices/cpu/events/cache-references
> /sys/devices/cpu/events/cpu-cycles
> + /sys/devices/cpu/events/instructions
> + /sys/devices/cpu/events/ref-cycles
> + /sys/devices/cpu/events/stalled-cycles-backend
> + /sys/devices/cpu/events/stalled-cycles-frontend
>
> Date: 2013/01/08
>
> Contact: Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
>
> -Description: Generic performance monitoring events
> +Description: Generic CPU performance monitoring events
>
> A collection of performance monitoring events that may be
> supported by many/most CPUs. These events can be monitored
> using the 'perf(1)' tool.
>
> - The contents of each file would look like:
> -
> - event=0xNNNN
> -
> - where 'N' is a hex digit and the number '0xNNNN' shows the
> - "raw code" for the perf event identified by the file's
> - "basename".
> + The format of these files matches that of
> + /sys/bus/event_source/devices/<dev>/events as described
> + previously in this file.
>
>
> What: /sys/devices/cpu/events/PM_1PLUS_PPC_CMPL
> diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-format b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format
> index 77f47ff..8f4c13f 100644
> --- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-format
> +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format
> @@ -15,6 +15,12 @@ Description:
> attr2 = 'config:0-7'
> attr3 = 'config:12-35'
>
> - Example: 'config1:1,6-10,44'
> + Example: event = 'config1:1,6-10,44'
> Defines contents of attribute that occupies bits 1,6-10,44 of
> perf_event_attr::config1.
> +
> + In this example, the events file would have the value
> + event=0x7f
> + to set all of the specified bits (they will be split up).
> + You would not use 0x10000007c2 (which is what the bits
> + actually passed into config1 would look like).
>

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