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SubjectRe: [PATCH V5] perf: Add PERF_SAMPLE_PHYS_ADDR
On Thu, Aug 17, 2017 at 02:17:23PM -0400, kan.liang@intel.com wrote:
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index a3b873f..6783c69 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -944,6 +944,8 @@ struct perf_sample_data {
>
> struct perf_regs regs_intr;
> u64 stack_user_size;
> +
> + u64 phys_addr;
> } ____cacheline_aligned;
>
> /* default value for data source */
> @@ -964,6 +966,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
> data->weight = 0;
> data->data_src.val = PERF_MEM_NA;
> data->txn = 0;
> + data->phys_addr = 0;
> }

So this is very unfortunate...

struct perf_sample_data {
u64 addr; /* 0 8 */
struct perf_raw_record * raw; /* 8 8 */
struct perf_branch_stack * br_stack; /* 16 8 */
u64 period; /* 24 8 */
u64 weight; /* 32 8 */
u64 txn; /* 40 8 */
union perf_mem_data_src data_src; /* 48 8 */
u64 type; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
u64 ip; /* 64 8 */
struct {
u32 pid; /* 72 4 */
u32 tid; /* 76 4 */
} tid_entry; /* 72 8 */
u64 time; /* 80 8 */
u64 id; /* 88 8 */
u64 stream_id; /* 96 8 */
struct {
u32 cpu; /* 104 4 */
u32 reserved; /* 108 4 */
} cpu_entry; /* 104 8 */
struct perf_callchain_entry * callchain; /* 112 8 */
struct perf_regs regs_user; /* 120 16 */
/* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
struct pt_regs regs_user_copy; /* 136 168 */
/* --- cacheline 4 boundary (256 bytes) was 48 bytes ago --- */
struct perf_regs regs_intr; /* 304 16 */
/* --- cacheline 5 boundary (320 bytes) --- */
u64 stack_user_size; /* 320 8 */

/* size: 384, cachelines: 6, members: 19 */
/* padding: 56 */
};


static inline void perf_sample_data_init(struct perf_sample_data *data,
u64 addr, u64 period)
{
/* remaining struct members initialized in perf_prepare_sample() */
data->addr = addr;
data->raw = NULL;
data->br_stack = NULL;
data->period = period;
data->weight = 0;
data->data_src.val = PERF_MEM_NA;
data->txn = 0;
}

You'll note that that only touches the first cacheline of the data
structure, and you just wrecked that. Back when I did that this made a
measurable difference.

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