Re: [PATCH 2/4] perf: Add mem_hops field in perf_mem_data_src structure

On 10/6/21 1:50 AM, Peter Zijlstra wrote:

On Tue, Oct 05, 2021 at 02:48:35PM +0530, Kajol Jain wrote:

quoted

Going forward, future generation systems can have more hierarchy
within the chip/package level but currently we don't have any data source
encoding field in perf, which can be used to represent this level of data.

Add a new field called 'mem_hops' in the perf_mem_data_src structure
which can be used to represent intra-chip/package or inter-chip/off-package
details. This field is of size 3 bits where PERF_MEM_HOPS_{NA, 0..6} value
can be used to present different hop levels data.

Also add corresponding macros to define mem_hop field values
and shift value.

Currently we define macro for HOPS_0 which corresponds
to data coming from another core but same chip.

For ex: Encodings for mem_hops fields with L2 cache:

L2			- local L2
L2 | REMOTE | HOPS_0	- remote core, same chip L2

Can we do s/chip/node/ ? Hops are something NUMA related, while chips
come in a bag or something :-)

Hi Peter,
  Sure, I will make this change in next version of this patch-set.

Thanks,
Kajol Jain

quoted

+/* hop level */
+#define PERF_MEM_HOPS_0		0x01 /* remote core, same chip */
+/* 2-7 available */
+#define PERF_MEM_HOPS_SHIFT	43