perf: POWER-event translation questions

Looking for feedback on this prototype for making POWER-specific event
translations available in sysfs. It is based on the patchset:

	https://lkml.org/lkml/2012/11/7/402

which makes the translations for _generic_ events in POWER available in sysfs:

Since this is in POWER7 specific code I am assigning the names given in the
POWER7 CPU spec for now.

I had earlier tried mapping these events to generic names outside sysfs:

	Power7 name		Generic name

	cmpl-stall-fxu		stalled-cycles-fixed-point
	cmpl-stall-lsu		stalled-cycles-load-store
	cmpl-stall-ifu		stalled-cycles-instruction-fetch
	cmpl-stall-bru 		stalled-cycles-branch-unit

But like Stephane Eranian pointed out mapping such events across architectures
can be confusing.

Another challenge I suspect we will have is the extremely long generic names
we could end up with as the events get more specific.

1. Can we have more than one name for an event ? i.e two sysfs entries,
   eg: 'cmpl-stall-fxu' and 'stalled-cycles-fixed-point' for an event ?

2. Can we allow hyphens in the {name} token  (please see my change to
   util/parse-events.l below). With this change, I can run:

	  perf stat -e cpu/cmplu-stall-bru /tmp/nop

   without any changes to the user level tool (parse-events.l) I have
   tested some common cases, not sure if it will break something :-)

   If we are going to create generic or arch specific sysfs entries in
   /sys/bus/event_source/devices/cpu/events, do we need to add corresponding
   entry in tools/perf/util/parse-events.l ?

Sukadev

---
 arch/powerpc/perf/power7-pmu.c |   13 +++++++++++++
 tools/perf/util/parse-events.l |    2 +-
 2 files changed, 14 insertions(+), 1 deletions(-)

On Thu, Nov 8, 2012 at 2:10 AM, Sukadev Bhattiprolu
<sukadev@linux.vnet.ibm.com> wrote:
>
>
> Looking for feedback on this prototype for making POWER-specific event
> translations available in sysfs. It is based on the patchset:
>
>         https://lkml.org/lkml/2012/11/7/402
>
> which makes the translations for _generic_ events in POWER available in sysfs:
>
> Since this is in POWER7 specific code I am assigning the names given in the
> POWER7 CPU spec for now.
>
> I had earlier tried mapping these events to generic names outside sysfs:
>
>         Power7 name             Generic name
>
>         cmpl-stall-fxu          stalled-cycles-fixed-point
>         cmpl-stall-lsu          stalled-cycles-load-store
>         cmpl-stall-ifu          stalled-cycles-instruction-fetch
>         cmpl-stall-bru          stalled-cycles-branch-unit
>
> But like Stephane Eranian pointed out mapping such events across architectures
> can be confusing.
>
> Another challenge I suspect we will have is the extremely long generic names
> we could end up with as the events get more specific.
>
> 1. Can we have more than one name for an event ? i.e two sysfs entries,
>    eg: 'cmpl-stall-fxu' and 'stalled-cycles-fixed-point' for an event ?
>
Yes, you can. What is really used is the content of the file and two files
can have the same content.

> 2. Can we allow hyphens in the {name} token  (please see my change to
>    util/parse-events.l below). With this change, I can run:
>
The current code does not support this but Andi fixed that in his HSW patch
and I use it for the PEBS-LL patch series as well.

>           perf stat -e cpu/cmplu-stall-bru /tmp/nop
>
>    without any changes to the user level tool (parse-events.l) I have
>    tested some common cases, not sure if it will break something :-)
>
>    If we are going to create generic or arch specific sysfs entries in
>    /sys/bus/event_source/devices/cpu/events, do we need to add corresponding
>    entry in tools/perf/util/parse-events.l ?
>
Shouldn't be necessary. perf should grab those events automatically from sysfs.
As per Jiri, the hardcoded tables are only used to support backward
compatibility
for kernels without sysfs event entries.

> Sukadev
>
> ---
>  arch/powerpc/perf/power7-pmu.c |   13 +++++++++++++
>  tools/perf/util/parse-events.l |    2 +-
>  2 files changed, 14 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/perf/power7-pmu.c b/arch/powerpc/perf/power7-pmu.c
> index aa9f588..9f46abc 100644
> --- a/arch/powerpc/perf/power7-pmu.c
> +++ b/arch/powerpc/perf/power7-pmu.c
> @@ -303,6 +303,10 @@ static void power7_disable_pmc(unsigned int pmc, unsigned long mmcr[])
>  #define        PM_LD_MISS_L1                   0x400f0
>  #define        PM_BRU_FIN                      0x10068
>  #define        PM_BRU_MPRED                    0x400f6
> +#define        PM_CMPLU_STALL_FXU              0x20014
> +#define        PM_CMPLU_STALL_LSU              0x20012
> +#define        PM_CMPLU_STALL_IFU              0x4004c
> +#define        PM_CMPLU_STALL_BRU              0x4004e
>
>  static int power7_generic_events[] = {
>         [PERF_COUNT_HW_CPU_CYCLES] =                    PM_CYC,
> @@ -369,6 +373,11 @@ EVENT_ATTR(cache-misses,               LD_MISS_L1);
>  EVENT_ATTR(branch-instructions,        BRU_FIN);
>  EVENT_ATTR(branch-misses,              BRU_MPRED);
>
> +EVENT_ATTR(cmplu-stall-fxu,            CMPLU_STALL_FXU);
> +EVENT_ATTR(cmplu-stall-lsu,            CMPLU_STALL_LSU);
> +EVENT_ATTR(cmplu-stall-ifu,            CMPLU_STALL_IFU);
> +EVENT_ATTR(cmplu-stall-bru,            CMPLU_STALL_BRU);
> +
>  static struct attribute *power7_events_attr[] = {
>         EVENT_PTR(CYC),
>         EVENT_PTR(GCT_NOSLOT_CYC),
> @@ -378,6 +387,10 @@ static struct attribute *power7_events_attr[] = {
>         EVENT_PTR(LD_MISS_L1),
>         EVENT_PTR(BRU_FIN),
>         EVENT_PTR(BRU_MPRED),
> +       EVENT_PTR(CMPLU_STALL_FXU),
> +       EVENT_PTR(CMPLU_STALL_LSU),
> +       EVENT_PTR(CMPLU_STALL_IFU),
> +       EVENT_PTR(CMPLU_STALL_BRU),
>         NULL,
>  };
>
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index c87efc1..1967bb2 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -80,7 +80,7 @@ event         [^,{}/]+
>  num_dec                [0-9]+
>  num_hex                0x[a-fA-F0-9]+
>  num_raw_hex    [a-fA-F0-9]+
> -name           [a-zA-Z_*?][a-zA-Z0-9_*?]*
> +name           [-a-zA-Z_*?][-a-zA-Z0-9_*?]*
>  modifier_event [ukhpGH]{1,8}
>  modifier_bp    [rwx]{1,3}
>
> --
> 1.7.1
>

On 09.11.12 11:26:26, Stephane Eranian wrote:
> On Thu, Nov 8, 2012 at 2:10 AM, Sukadev Bhattiprolu
> <sukadev@linux.vnet.ibm.com> wrote:

> > 2. Can we allow hyphens in the {name} token  (please see my change to
> >    util/parse-events.l below). With this change, I can run:
> >
> The current code does not support this but Andi fixed that in his HSW patch
> and I use it for the PEBS-LL patch series as well.
>
> >           perf stat -e cpu/cmplu-stall-bru /tmp/nop
> >
> >    without any changes to the user level tool (parse-events.l) I have
> >    tested some common cases, not sure if it will break something :-)

But ...

> > diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> > index c87efc1..1967bb2 100644
> > --- a/tools/perf/util/parse-events.l
> > +++ b/tools/perf/util/parse-events.l
> > @@ -80,7 +80,7 @@ event         [^,{}/]+
> >  num_dec                [0-9]+
> >  num_hex                0x[a-fA-F0-9]+
> >  num_raw_hex    [a-fA-F0-9]+
> > -name           [a-zA-Z_*?][a-zA-Z0-9_*?]*
> > +name           [-a-zA-Z_*?][-a-zA-Z0-9_*?]*
                     ^

... I wouldn't allow hyphens at the beginning of a name.

And, I am wondering if parsing reserved names like 'cpu-cycles' works
too, e.g. cpu/cpu-cycles-foobar/. There are many reserved words in the
lexer with hyphens in it. This might cause unexpected problems.

-Robert