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SubjectRe: [PATCH v6 3/4] perf Documentation: add event parameters
On Sun, Dec 21, 2014 at 11:49:26PM -0800, Sukadev Bhattiprolu wrote:
> From: Cody P Schafer <cody@linux.vnet.ibm.com>
>
> Event parameters are a basic way for partial events to be specified in
> sysfs with per-event names given to the fields that need to be filled in
> when using a particular event.
>
> It is intended for supporting cases where the single 'cpu' parameter is
> insufficient. For example, POWER 8 has events for physical
> sockets/cores/cpus that are accessible from with virtual machines. To
> keep using the single 'cpu' parameter we'd need to perform a mapping
> between Linux's cpus and the physical machine's cpus (in this case
> Linux is running under a hypervisor). This isn't possible because
> bindings between our cpus and physical cpus may not be fixed, and we
> probably won't have a "cpu" on each physical cpu.
>
> Changelog[v6]
> Update event description to explain how required parameters
> are displayed.
>
> CC: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> CC: Haren Myneni <hbabu@us.ibm.com>
> CC: Cody P Schafer <dev@codyps.com>
> Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
> ---
> Documentation/ABI/testing/sysfs-bus-event_source-devices-events | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> index 20979f8..47ad2a1 100644
> --- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
> @@ -52,12 +52,18 @@ Description: Per-pmu performance monitoring events specific to the running syste
> event=0x2abc
> event=0x423,inv,cmask=0x3
> domain=0x1,offset=0x8,starting_index=0xffff
> + domain=0x1,offset=0x8,core=?
>
> Each of the assignments indicates a value to be assigned to a
> particular set of bits (as defined by the format file
> corresponding to the <term>) in the perf_event structure passed
> to the perf_open syscall.
>
> + In the case of the last example, a value replacing "?" would
> + need to be provided by the user selecting the particular event.
> + This is referred to as "event parameterization". All
> + non-numerical values indicate an event parameter.

I see.. here's the glitch ;-) I thought we agreed on forcing '?'
as the value for param events, not 'All non-numerical values'

thanks,
jirka


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