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SubjectRe: new syntax for perf event
On Thu, Jan 05, 2012 at 03:10:56PM +0100, Peter Zijlstra wrote:
> On Wed, 2011-12-21 at 17:16 +0100, Jiri Olsa wrote:
> > grammar
>
> yacc/bison notation it seems.. lemme get the rules for that.
>
> > -------
> > events:
> > event_mod ',' event_mod | event_mod
>
> events = event_mod, {',' , event_mod};
>
> would be the EBNF variant for allowing inf repetition, not sure how to
> express that, it seems to want a recursive rule which I'm not sure I
> see. The way I read your thing it only allows 1 or 2 events.

aargh, sure we want more than 2 events ;)
should have been something like:

events: events ',' event_mod | event_mod


>
> >
> > event_mod:
> > event | event ':' modifier
>
>
> event_mod = event, [':' , modifier];
>
> Would be the EBNF thing, and I think your rule does indeed match that.
>
> > event:
> > event_symbol |
> > event_cache |
> > 'cpu' '/' event_cpu |
> > 'tracepoint' '/' event_tracepoint
> > 'breakpoint' '/' event_breakpoint
>
> I think I'd like to see something like:
>
> event = pmu, '/', event_config
> | event_symbol | event_cache;
>
> pmu = ? ls /sys/bus/event_source/devices ?;

ok


> (* maybe add some aliasses like you suggest *)
>
> event_config = (event_predef | event_term), {',', event_term};
>
> event_predef = ? special name -> raw mapping read from somewhere ?;
>
> event_term = event_sym, '=', value;
>
> event_sym = "config" | "config1" | "config2"
> | ? contents of /sys/bus/event_source/devices/$pmu/format ?;

anyone working on the 'format' stuff? ;) I guess thats the place,
where we can stay with hardcoded config[12] so far.. right?


>
> value = integer | hexint;
>
>
> > event_symbol:
> > cpu-cycles|cycles
> > stalled-cycles-frontend|idle-cycles-frontend
> > stalled-cycles-backend|idle-cycles-backend
> > instructions
> > cache-references
> > cache-misses
> > branch-instructions|branches
> > branch-misses
> > bus-cycles
> > cpu-clock
> > task-clock
> > page-faults|faults
> > minor-faults
> > major-faults
> > context-switches|cs
> > cpu-migrations|migrations
> > alignment-faults
> > emulation-faults
> >
> > event_cache:
> > cache_type
> > cache_type '-' cache_result_op
> > cache_type '-' cache_result_op '-' cache_result_op
>
> I'd write that as:
>
> event_cache = cache_type, '-', cache_mod, ['-', cache_xs];
>
> cache_type = cache_l1d | cache_l1i | cache_llc
> | cache_dtlb | cache_itlb
> | cache_branch | cache_node;
>
> cache_mod = cache_load | cache_store | cache_prefetch;
>
> cache_xs = cache_accesses | cache_misses;
>
> cache_l1d = "L1-dcache" | ... ;

ok


>
> etc..
>
>
> > event_cpu:
> > 'raw' ',' event_cpu_def
> > 'hw' ',' event_cpu_def
> > 'cache' ',' event_cpu_def
>
> I think these are superfluous and we could deduce them from the actual
> event_term's used. Something using "config" will be a raw event etc..

ok


>
> >
> > event_cpu_def:
> > event_cpu_ass ',' event_cpu_ass |
> > event_cpu_ass
> >
> > event_cpu_ass:
> > event_cpu_elem '=' value
>
> Hehehe, you said 'ass', hehe.
eh.. you're seeing things ;) just best fitting abbrev..


>
>
> > event_tracepoint:
> > system ':' tracepoint
> >
> > event_breakpoint:
> > addr ':' type
>
> Right, something like that.
>
> >
> > modifier:
> > [ukhp]{1,4}
>
> I think you need at least 5, or you can write it like:
>
> modifier = ['u'], ['k'], ['h'], [3*'p'];
>
> Also, I think we grew a few more modifiers with some of the perf kvm
> guest muck.

yep, I'll update it..
I'll prepare another patch version including above changes

thanks,
jirka


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