Re: [PATCH v7 07/18] perf: add generic memory sampling interface

From: Stephane Eranian
Date: Fri Jan 25 2013 - 10:30:31 EST

On Fri, Jan 25, 2013 at 10:01 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> * Stephane Eranian <eranian@xxxxxxxxxx> wrote:
>
>> This patch adds PERF_SAMPLE_DSRC.
>>
>> PERF_SAMPLE_DSRC collects the data source, i.e., where
>> did the data associated with the sampled instruction
>> come from. Information is stored in a perf_mem_dsrc
>> structure. It contains opcode, mem level, tlb, snoop,
>> lock information, subject to availability in hardware.
>>
>> Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
>> ---
>> include/linux/perf_event.h | 2 ++
>> include/uapi/linux/perf_event.h | 68 +++++++++++++++++++++++++++++++++++++--
>> kernel/events/core.c | 6 ++++
>> 3 files changed, 74 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
>> index bb2429d..8fe4610 100644
>> --- a/include/linux/perf_event.h
>> +++ b/include/linux/perf_event.h
>> @@ -579,6 +579,7 @@ struct perf_sample_data {
>> u32 reserved;
>> } cpu_entry;
>> u64 period;
>> + union perf_mem_dsrc dsrc;
>> struct perf_callchain_entry *callchain;
>> struct perf_raw_record *raw;
>> struct perf_branch_stack *br_stack;
>> @@ -599,6 +600,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
>> data->regs_user.regs = NULL;
>> data->stack_user_size = 0;
>> data->weight = 0;
>> + data->dsrc.val = 0;
>> }
>>
>> extern void perf_output_sample(struct perf_output_handle *handle,
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index 3e6c394..3e4844c 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -133,9 +133,9 @@ enum perf_event_sample_format {
>> PERF_SAMPLE_REGS_USER = 1U << 12,
>> PERF_SAMPLE_STACK_USER = 1U << 13,
>> PERF_SAMPLE_WEIGHT = 1U << 14,
>> + PERF_SAMPLE_DSRC = 1U << 15,
>>
>> - PERF_SAMPLE_MAX = 1U << 15, /* non-ABI */
>> -
>> + PERF_SAMPLE_MAX = 1U << 16, /* non-ABI */
>> };
>>
>> /*
>> @@ -591,6 +591,7 @@ enum perf_event_type {
>> * u64 dyn_size; } && PERF_SAMPLE_STACK_USER
>> *
>> * { u64 weight; } && PERF_SAMPLE_WEIGHT
>> + * { u64 dsrc; } && PERF_SAMPLE_DSRC
>> * };
>> */
>> PERF_RECORD_SAMPLE = 9,
>> @@ -616,4 +617,67 @@ enum perf_callchain_context {
>> #define PERF_FLAG_FD_OUTPUT (1U << 1)
>> #define PERF_FLAG_PID_CGROUP (1U << 2) /* pid=cgroup id, per-cpu mode only */
>>
>> +union perf_mem_dsrc {
>> + __u64 val;
>> + struct {
>> + __u64 mem_op:5, /* type of opcode */
>> + mem_lvl:14, /* memory hierarchy level */
>> + mem_snoop:5, /* snoop mode */
>> + mem_lock:2, /* lock instr */
>> + mem_dtlb:7, /* tlb access */
>> + mem_rsvd:31;
>> + };
>> +};
>> +
>> +/* type of opcode (load/store/prefetch,code) */
>> +#define PERF_MEM_OP_NA 0x01 /* not available */
>> +#define PERF_MEM_OP_LOAD 0x02 /* load instruction */
>> +#define PERF_MEM_OP_STORE 0x04 /* store instruction */
>> +#define PERF_MEM_OP_PFETCH 0x08 /* prefetch */
>> +#define PERF_MEM_OP_EXEC 0x10 /* code (execution) */
>> +#define PERF_MEM_OP_SHIFT 0
>> +
>> +/* memory hierarchy (memory level, hit or miss) */
>> +#define PERF_MEM_LVL_NA 0x01 /* not available */
>> +#define PERF_MEM_LVL_HIT 0x02 /* hit level */
>> +#define PERF_MEM_LVL_MISS 0x04 /* miss level */
>> +#define PERF_MEM_LVL_L1 0x08 /* L1 */
>> +#define PERF_MEM_LVL_LFB 0x10 /* Line Fill Buffer */
>> +#define PERF_MEM_LVL_L2 0x20 /* L2 hit */
>> +#define PERF_MEM_LVL_L3 0x40 /* L3 hit */
>> +#define PERF_MEM_LVL_LOC_RAM 0x80 /* Local DRAM */
>> +#define PERF_MEM_LVL_REM_RAM1 0x100 /* Remote DRAM (1 hop) */
>> +#define PERF_MEM_LVL_REM_RAM2 0x200 /* Remote DRAM (2 hops) */
>> +#define PERF_MEM_LVL_REM_CCE1 0x400 /* Remote Cache (1 hop) */
>> +#define PERF_MEM_LVL_REM_CCE2 0x800 /* Remote Cache (2 hops) */
>> +#define PERF_MEM_LVL_IO 0x1000 /* I/O memory */
>> +#define PERF_MEM_LVL_UNC 0x2000 /* Uncached memory */
>> +#define PERF_MEM_LVL_SHIFT 5
>> +
>> +/* snoop mode */
>> +#define PERF_MEM_SNOOP_NA 0x01 /* not available */
>> +#define PERF_MEM_SNOOP_NONE 0x02 /* no snoop */
>> +#define PERF_MEM_SNOOP_HIT 0x04 /* snoop hit */
>> +#define PERF_MEM_SNOOP_MISS 0x08 /* snoop miss */
>> +#define PERF_MEM_SNOOP_HITM 0x10 /* snoop hit modified */
>> +#define PERF_MEM_SNOOP_SHIFT 19
>> +
>> +/* locked instruction */
>> +#define PERF_MEM_LOCK_NA 0x01 /* not available */
>> +#define PERF_MEM_LOCK_LOCKED 0x02 /* locked transaction */
>> +#define PERF_MEM_LOCK_SHIFT 24
>> +
>> +/* TLB access */
>> +#define PERF_MEM_TLB_NA 0x01 /* not available */
>> +#define PERF_MEM_TLB_HIT 0x02 /* hit level */
>> +#define PERF_MEM_TLB_MISS 0x04 /* miss level */
>> +#define PERF_MEM_TLB_L1 0x08 /* L1 */
>> +#define PERF_MEM_TLB_L2 0x10 /* L2 */
>> +#define PERF_MEM_TLB_WK 0x20 /* Hardware Walker*/
>> +#define PERF_MEM_TLB_OS 0x40 /* OS fault handler */
>> +#define PERF_MEM_TLB_SHIFT 26
>> +
>> +#define PERF_MEM_S(a, s) \
>> + (((u64)PERF_MEM_##a##_##s) << PERF_MEM_##a##_SHIFT)
>> +
>
> Would be nice to get feedback from PowerPC folks to see how well
> this matches their memory profiling hw capabilities?
>
I agree, I tried to remain as generic as possible here but I probably
don't have all the possibilities covered. I remember IBM asking
me about the categories a long time ago. Haven't heard anything since then.

> I suspect there's a lot of differences, but one can always hope
> ...
>
> If there's some hope for unification we could at least shape it
> in a way that they could pick up and extend.
>
Agreed.
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