Messages in this thread | | | Date | Wed, 27 Apr 2011 12:03:12 -0700 | Subject | Re: [PATCH] perf events: Add stalled cycles generic event - PERF_COUNT_HW_STALLED_CYCLES | From | Arun Sharma <> |
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On Wed, Apr 27, 2011 at 8:48 AM, Ingo Molnar <mingo@elte.hu> wrote:
> >> The other issue I had to deal with was UOPS_RETIRED > UOPS_EXECUTED >> condition. I believe this is caused by what AMD calls sideband stack >> optimizer and Intel calls dedicated stack manager (i.e. UOPS executed outside >> the main pipeline). A recursive fibonacci(30) is a good test case for >> reproducing this. > > So the PORT015+234 sum is not precise? The definition seems to be rather firm: > > Counts number of Uops executed that where issued on port 2, 3, or 4. > Counts number of Uops executed that where issued on port 0, 1, or 5. >
There is some work done outside of the main out of order engine for power optimization reasons:
Described as dedicated stack engine here: http://www.intel.com/technology/itj/2003/volume07issue02/art03_pentiumm/vol7iss2_art03.pdf
However, I can't seem to be able to reproduce this behavior using a micro benchmark right now:
# cat foo.s .text .global main main: 1: push %rax push %rbx push %rcx push %rdx pop %rax pop %rbx pop %rcx pop %rdx jmp 1b
Performance counter stats for './foo':
7,755,881,073 UOPS_ISSUED:ANY:t=1 (scaled from 79.98%) 10,569,957,988 UOPS_RETIRED:ANY:t=1 (scaled from 79.96%) 9,155,400,383 UOPS_EXECUTED:PORT234_CORE (scaled from 80.02%) 2,594,206,312 UOPS_EXECUTED:PORT015:t=1 (scaled from 80.02%)
Perhaps I was thinking of UOPS_ISSUED < UOPS_RETIRED.
In general, UOPS_RETIRED (or instruction retirement in general) is the "source of truth" in an otherwise crazy world and might be more interesting as a generalized event that works on multiple architectures.
-Arun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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