linux-kernel - Re: [PATCH 8/8][v4] powerpc/perf: Export Power7 memory hierarchy info to user space.

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Date:	Wed, 18 Sep 2013 16:17:23 +0530
From:	Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
CC:	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <michaele@....ibm.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 8/8][v4] powerpc/perf: Export Power7 memory hierarchy
 info to user space.

On 09/14/2013 06:19 AM, Sukadev Bhattiprolu wrote:
> On Power7, the DCACHE_SRC field in MMCRA register identifies the memory
> hierarchy level (eg: L2, L3 etc) from which a data-cache miss for a
> marked instruction was satisfied.
> 
> Use the 'perf_mem_data_src' object to export this hierarchy level to user
> space. Some memory hierarchy levels in Power7 don't map into the arch-neutral
> levels. However, since newer generation of the processor (i.e. Power8) uses
> fewer levels than in Power7, we don't really need to define new hierarchy
> levels just for Power7.
> 
> We instead, map as many levels as possible and approximate the rest. See
> comments near dcache-src_map[] in the patch.
> 
> Usage:
> 
> 	perf record -d -e 'cpu/PM_MRK_GRP_CMPL/' <application>
> 	perf report -n --mem-mode --sort=mem,sym,dso,symbol_daddr,dso_daddr"
> 
> 		For samples involving load/store instructions, the memory
> 		hierarchy level is shown as "L1 hit", "Remote RAM hit" etc.
> 	# or
> 
> 	perf record --data <application>
> 	perf report -D
> 
> 		Sample records contain a 'data_src' field which encodes the
> 		memory hierarchy level: Eg: data_src 0x442 indicates
> 		MEM_OP_LOAD, MEM_LVL_HIT, MEM_LVL_L2 (i.e load hit L2).

Successfully built and boot tested this entire patchset both on a P7 and P8 system.
Running some sample tests with ebizzy micro benchmark. Till now got only 0x142 and
0x0 values for data_src object for the sample records. Will experiment around bit
more on P7 and P8 systems and post the results.

Regards
Anshuman 

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