Re: [PATCH 1/2] perf/Power7: Save dcache_src fields in sample record.

From: Anshuman Khandual
Date: Mon Jun 10 2013 - 04:04:04 EST


>
> AFAICT, Power7 supports one extra level in the cache-hierarchy, so we propose
> to add a new cache level, REM_CCE3 shown above.
>
> To maintain consistency in terminology (i.e 2-hops = remote, 3-hops = distant),
> I propose leaving the REM_MEM1 unused and adding another level, REM_MEM3.
>

Agreed.

> Further, in the above REM_CCE1 case, Power7 can also identify if the data came
> from the L2 or L3 cache of another core on the same chip. To describe this to
> user space, we propose to set ->mem_lvl to:
>
> PERF_MEM_LVL_REM_CCE1|PERF_MEM_LVL_L2
>
> PERF_MEM_LVL_REM_CCE1|PERF_MEM_LVL_L3
>
> Either that or we could leave REM_CCE1 unused in Power and add two more levels:
>
> PERF_MEM_XLVL_REM_L2_CCE1
> PERF_MEM_XLVL_REM_L3_CCE1
>
> The former approach seems less confusing and this patch uses that approach.
>

Yeah, the former approach is simpler and makes sense.


> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/perf_event_server.h | 2 +
> arch/powerpc/perf/core-book3s.c | 4 +
> arch/powerpc/perf/power7-pmu.c | 81 ++++++++++++++++++++++++++
> include/uapi/linux/perf_event.h | 12 +++-
> 4 files changed, 97 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/perf_event_server.h b/arch/powerpc/include/asm/perf_event_server.h
> index f265049..f2d162b 100644
> --- a/arch/powerpc/include/asm/perf_event_server.h
> +++ b/arch/powerpc/include/asm/perf_event_server.h
> @@ -37,6 +37,8 @@ struct power_pmu {
> void (*config_bhrb)(u64 pmu_bhrb_filter);
> void (*disable_pmc)(unsigned int pmc, unsigned long mmcr[]);
> int (*limited_pmc_event)(u64 event_id);
> + void (*get_mem_data_src)(struct perf_sample_data *data,
> + struct pt_regs *regs);
> u32 flags;
> const struct attribute_group **attr_groups;
> int n_generic;
> diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
> index 426180b..7778fa9 100644
> --- a/arch/powerpc/perf/core-book3s.c
> +++ b/arch/powerpc/perf/core-book3s.c
> @@ -1632,6 +1632,10 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
> data.br_stack = &cpuhw->bhrb_stack;
> }
>
> + if (event->attr.sample_type & PERF_SAMPLE_DATA_SRC &&
> + ppmu->get_mem_data_src)
> + ppmu->get_mem_data_src(&data, regs);
> +
> if (perf_event_overflow(event, &data, regs))
> power_pmu_stop(event, 0);
> }
> diff --git a/arch/powerpc/perf/power7-pmu.c b/arch/powerpc/perf/power7-pmu.c
> index 3c475d6..af92bfe 100644
> --- a/arch/powerpc/perf/power7-pmu.c
> +++ b/arch/powerpc/perf/power7-pmu.c
> @@ -209,6 +209,85 @@ static int power7_get_alternatives(u64 event, unsigned int flags, u64 alt[])
> return nalt;
> }
>
> +#define POWER7_MMCRA_PEMPTY (0x1L << 63)
> +#define POWER7_MMCRA_FIN_STALL (0x1L << 62)
> +#define POWER7_MMCRA_CMPL_STALL (0x1L << 61)
> +#define POWER7_MMCRA_STALL_REASON_MASK (0xFL << 60)
> +
> +#define POWER7_MMCRA_DCACHE_MISS (0x1L << 55)
> +
> +#define POWER7_MMCRA_DCACHE_SRC_SHIFT 51
> +#define POWER7_MMCRA_DCACHE_SRC_MASK (0xFL << POWER7_MMCRA_DCACHE_SRC_SHIFT)
> +
> +#define POWER7_MMCRA_MDTLB_MISS (0x1L << 50)
> +
> +#define POWER7_MMCRA_MDTLB_SRC_SHIFT 46
> +#define POWER7_MMCRA_MDTLB_SRC_MASK (0xFL << POWER7_MMCRA_MDTLB_SRC_SHIFT)
> +
> +#define POWER7_MMCRA_MDERAT_MISS (0x1L<< 45)
> +#define POWER7_MMCRA_MLSU_REJ (0x1L<< 44)
> +
> +/* and so on */
> +
> +/*
> + * Map DCACHE_SRC fields to the Linux memory hierarchy levels.
> + *
> + * Bits 9..12 in the MMCRA indicate the source of a data-cache entry, with
> + * each of the 16 possible values referring to a specific source. Eg: if
> + * the 4-bits have the value 1 (0b0001), the dcache entry was found local
> + * L3 cache.
> + *
> + * We use the table, dcache_src_map, to map this value 1 to PERF_MEM_LVL_L3,
> + * the arch-neutral representation of the L3 cache.
> + *
> + * Similarly, in case of marked data TLB miss, bits 14..17 of the MMCRA
> + * indicate the load source of a marked DTLB entry. dtlb_src_map[] gives
> + * the mapping to the arch-neutral values of the TLB source.


Where did you define dtlb_src_map[] ?

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