linux-kernel - Re: [PATCH 1/4] perf: Add comment about current state of PERF_MEM_LVL

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Date:   Tue, 5 Oct 2021 15:18:40 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org, jolsa@...nel.org,
        namhyung@...nel.org, ak@...ux.intel.com
Cc:     linux-perf-users@...r.kernel.org, maddy@...ux.ibm.com,
        atrajeev@...ux.vnet.ibm.com, rnsastry@...ux.ibm.com,
        yao.jin@...ux.intel.com, ast@...nel.org, daniel@...earbox.net,
        songliubraving@...com, kan.liang@...ux.intel.com,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        paulus@...ba.org
Subject: Re: [PATCH 1/4] perf: Add comment about current state of
 PERF_MEM_LVL_* namespace and remove an extra line

Hi,
  Sorry I missed to update correct version details.

Link to the previous patch-set, where discussion related to addition of
new data source encoding field 'mem_hops' happened:

https://lkml.org/lkml/2021/9/4/37

Changelog:

- Rather then adding new macros for L2.1/L3.1 (same chip, different
core) entries as part of field lvlnum, we are introducing new field
called 'mem_hops' which can be used to get hops
level data(intra-chip/package or inter-chip/off-package details).
As suggested by Peter Zijlstra.

- Using OnChip to denote data accesses from 'another core of same chip'
  is not too clear. Update it to 'remote core, same chip' as pointed by
  Michael Ellerman.

- Update the fix patch of correcting data source encodings to use new
added field 'mem_hops'.

Thanks,
Kajol Jain


On 10/5/21 2:48 PM, Kajol Jain wrote:
> Add a comment about PERF_MEM_LVL_* namespace being depricated
> to some extent in favour of added PERF_MEM_{LVLNUM_,REMOTE_,SNOOPX_}
> fields.
> 
> Remove an extra line present in perf_mem__lvl_scnprintf function.
> 
> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
> ---
>  include/uapi/linux/perf_event.h       | 8 +++++++-
>  tools/include/uapi/linux/perf_event.h | 8 +++++++-
>  tools/perf/util/mem-events.c          | 1 -
>  3 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index f92880a15645..e1701e9c7858 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -1241,7 +1241,13 @@ union perf_mem_data_src {
>  #define PERF_MEM_OP_EXEC	0x10 /* code (execution) */
>  #define PERF_MEM_OP_SHIFT	0
>  
> -/* memory hierarchy (memory level, hit or miss) */
> +/*
> + * PERF_MEM_LVL_* namespace being depricated to some extent in the
> + * favour of newer composite PERF_MEM_{LVLNUM_,REMOTE_,SNOOPX_} fields.
> + * Supporting this namespace inorder to not break defined ABIs.
> + *
> + * 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  */
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index f92880a15645..e1701e9c7858 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -1241,7 +1241,13 @@ union perf_mem_data_src {
>  #define PERF_MEM_OP_EXEC	0x10 /* code (execution) */
>  #define PERF_MEM_OP_SHIFT	0
>  
> -/* memory hierarchy (memory level, hit or miss) */
> +/*
> + * PERF_MEM_LVL_* namespace being depricated to some extent in the
> + * favour of newer composite PERF_MEM_{LVLNUM_,REMOTE_,SNOOPX_} fields.
> + * Supporting this namespace inorder to not break defined ABIs.
> + *
> + * 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  */
> diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
> index f0e75df72b80..ff7289e28192 100644
> --- a/tools/perf/util/mem-events.c
> +++ b/tools/perf/util/mem-events.c
> @@ -320,7 +320,6 @@ int perf_mem__lvl_scnprintf(char *out, size_t sz, struct mem_info *mem_info)
>  	/* already taken care of */
>  	m &= ~(PERF_MEM_LVL_HIT|PERF_MEM_LVL_MISS);
>  
> -
>  	if (mem_info && mem_info->data_src.mem_remote) {
>  		strcat(out, "Remote ");
>  		l += 7;
>