Subject: Re: [PATCH v2] perf mem/c2c: Fix perf_mem_events to support powerpc

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Tue, 29 Jan 2019 15:17:32 +0100

Em Tue, Jan 29, 2019 at 02:42:36PM +0100, Jiri Olsa escreveu:
> On Tue, Jan 29, 2019 at 06:54:12PM +0530, Ravi Bangoria wrote:
> > Powerpc hw does not have inbuilt latency filter (--ldlat) for mem-load
> > event and, perf_mem_events by default includes ldlat=30 which is
> > causing failure on powerpc. Refactor code to support perf mem/c2c on
> > powerpc.
> > 
> > This patch depends on kernel side changes done my Madhavan:
> > https://lists.ozlabs.org/pipermail/linuxppc-dev/2018-December/182596.html
> > 
> > Signed-off-by: Ravi Bangoria <[email-masked]>
> > ---
> 
> Acked-by: Jiri Olsa <[email-masked]>

Applied to perf/urgent, as soon as the kernel bits are there tooling
will be ready.

- Arnaldo
 
> thanks,
> jirka
> 
> >  tools/perf/Documentation/perf-c2c.txt     | 16 ++++++++++++----
> >  tools/perf/Documentation/perf-mem.txt     |  2 +-
> >  tools/perf/arch/powerpc/util/Build        |  1 +
> >  tools/perf/arch/powerpc/util/mem-events.c | 11 +++++++++++
> >  tools/perf/util/mem-events.c              |  2 +-
> >  5 files changed, 26 insertions(+), 6 deletions(-)
> >  create mode 100644 tools/perf/arch/powerpc/util/mem-events.c
> > 
> > diff --git a/tools/perf/Documentation/perf-c2c.txt b/tools/perf/Documentation/perf-c2c.txt
> > index 095aebd..e6150f2 100644
> > --- a/tools/perf/Documentation/perf-c2c.txt
> > +++ b/tools/perf/Documentation/perf-c2c.txt
> > @@ -19,8 +19,11 @@ C2C stands for Cache To Cache.
> >  The perf c2c tool provides means for Shared Data C2C/HITM analysis. It allows
> >  you to track down the cacheline contentions.
> >  
> > -The tool is based on x86's load latency and precise store facility events
> > -provided by Intel CPUs. These events provide:
> > +On x86, the tool is based on load latency and precise store facility events
> > +provided by Intel CPUs. On PowerPC, the tool uses random instruction sampling
> > +with thresholding feature.
> > +
> > +These events provide:
> >    - memory address of the access
> >    - type of the access (load and store details)
> >    - latency (in cycles) of the load access
> > @@ -46,7 +49,7 @@ RECORD OPTIONS
> >  
> >  -l::
> >  --ldlat::
> > -	Configure mem-loads latency.
> > +	Configure mem-loads latency. (x86 only)
> >  
> >  -k::
> >  --all-kernel::
> > @@ -119,11 +122,16 @@ Following perf record options are configured by default:
> >    -W,-d,--phys-data,--sample-cpu
> >  
> >  Unless specified otherwise with '-e' option, following events are monitored by
> > -default:
> > +default on x86:
> >  
> >    cpu/mem-loads,ldlat=30/P
> >    cpu/mem-stores/P
> >  
> > +and following on PowerPC:
> > +
> > +  cpu/mem-loads/
> > +  cpu/mem-stores/
> > +
> >  User can pass any 'perf record' option behind '--' mark, like (to enable
> >  callchains and system wide monitoring):
> >  
> > diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt
> > index f8d2167..199ea0f 100644
> > --- a/tools/perf/Documentation/perf-mem.txt
> > +++ b/tools/perf/Documentation/perf-mem.txt
> > @@ -82,7 +82,7 @@ RECORD OPTIONS
> >  	Be more verbose (show counter open errors, etc)
> >  
> >  --ldlat <n>::
> > -	Specify desired latency for loads event.
> > +	Specify desired latency for loads event. (x86 only)
> >  
> >  In addition, for report all perf report options are valid, and for record
> >  all perf record options.
> > diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
> > index 2e659531..ba98bd0 100644
> > --- a/tools/perf/arch/powerpc/util/Build
> > +++ b/tools/perf/arch/powerpc/util/Build
> > @@ -2,6 +2,7 @@ libperf-y += header.o
> >  libperf-y += sym-handling.o
> >  libperf-y += kvm-stat.o
> >  libperf-y += perf_regs.o
> > +libperf-y += mem-events.o
> >  
> >  libperf-$(CONFIG_DWARF) += dwarf-regs.o
> >  libperf-$(CONFIG_DWARF) += skip-callchain-idx.o
> > diff --git a/tools/perf/arch/powerpc/util/mem-events.c b/tools/perf/arch/powerpc/util/mem-events.c
> > new file mode 100644
> > index 0000000..f1194fc
> > --- /dev/null
> > +++ b/tools/perf/arch/powerpc/util/mem-events.c
> > @@ -0,0 +1,11 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include "mem-events.h"
> > +
> > +/* PowerPC does not support 'ldlat' parameter. */
> > +char *perf_mem_events__name(int i)
> > +{
> > +	if (i == PERF_MEM_EVENTS__LOAD)
> > +		return (char *) "cpu/mem-loads/";
> > +
> > +	return (char *) "cpu/mem-stores/";
> > +}
> > diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
> > index 93f74d8..42c3e5a 100644
> > --- a/tools/perf/util/mem-events.c
> > +++ b/tools/perf/util/mem-events.c
> > @@ -28,7 +28,7 @@ struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
> >  static char mem_loads_name[100];
> >  static bool mem_loads_name__init;
> >  
> > -char *perf_mem_events__name(int i)
> > +char * __weak perf_mem_events__name(int i)
> >  {
> >  	if (i == PERF_MEM_EVENTS__LOAD) {
> >  		if (!mem_loads_name__init) {
> > -- 
> > 1.8.3.1
> > 

-- 

- Arnaldo