Re: [PATCH v2 08/19] perf, tools: Expression parser enhancements for metrics

Jiri Olsa
2017-08-23T17:43:05Z

On Fri, Aug 11, 2017 at 04:26:23PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> Enhance the expression parser for more complex metric formulas.
>
> - Support python style IF ELSE operators
> - Add an #SMT_On magic variable for formulas that depend on the SMT
> status.
>
> Example: 4 *( CPU_CLK_UNHALTED.THREAD_ANY / 2 ) if #SMT_on else cycles
>
> - Support MIN/MAX operations
>
> Example: min(1 , IDQ.MITE_UOPS / ( UPI * 16 * ( ICACHE.HIT + ICACHE.MISSES ) / 4.0 ) )
>
> This is useful to fix up problems caused by multiplexing.
>
> - Support | & ^ operators
> - Minor cleanups and fixes
> - Support an \ escape for operators. This allows to specify event names
> like c2-residency
> - Support @ as an alternative for / to be able to specify pmus without
> conflicts with operators (like msr/tsc/ as msr@tsc@)
>
> Example: (cstate_core@c3\\-residency@ / msr@tsc@) * 100
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> tools/perf/tests/expr.c | 5 ++++
> tools/perf/util/expr.y | 61 ++++++++++++++++++++++++++++++++++++++++++++-----
> 2 files changed, 60 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> index 6c6a3749aaf6..e75365098f23 100644
> --- a/tools/perf/tests/expr.c
> +++ b/tools/perf/tests/expr.c
> @@ -31,6 +31,11 @@ int test__expr(int subtest __maybe_unused)
> ret |= test(&ctx, "(BAR/2)%2", 1);
> ret |= test(&ctx, "1 - -4", 5);
> ret |= test(&ctx, "(FOO-1)*2 + (BAR/2)%2 - -4", 5);
> + ret |= test(&ctx, "1-1 | 1", 1);
> + ret |= test(&ctx, "1-1 & 1", 0);
> + ret |= test(&ctx, "min(1,2) + 1", 2);
> + ret |= test(&ctx, "max(1,2) + 1", 3);
> + ret |= test(&ctx, "1+1 if 3*4 else 0", 2);

fyi I'm getting on Arnaldo's tree 'syntax error' but test is passing

[jolsa@krava perf]$ ./perf test expr -v
6: Simple expression parser :
--- start ---
test child forked, pid 1520
syntax error
test child finished with 0
---- end ----
Simple expression parser: Ok

jirka