linux-kernel - Re: [PATCH v10 1/7] perf/core: Define the common branch type classification

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Date:   Tue, 18 Jul 2017 12:54:18 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Jin Yao <yao.jin@...ux.intel.com>, jolsa@...nel.org,
        peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v10 1/7] perf/core: Define the common branch type
 classification

Em Tue, Jul 18, 2017 at 07:31:37PM +1000, Michael Ellerman escreveu:
> Jin Yao <yao.jin@...ux.intel.com> writes:
> 
> > It is often useful to know the branch types while analyzing branch
> > data. For example, a call is very different from a conditional branch.
> >
> > Currently we have to look it up in binary while the binary may later
> > not be available and even the binary is available but user has to take
> > some time. It is very useful for user to check it directly in perf
> > report.
> >
> > Perf already has support for disassembling the branch instruction
> > to get the x86 branch type.
> >
> > To keep consistent on kernel and userspace and make the classification
> > more common, the patch adds the common branch type classification
> > in perf_event.h.
> >
> > The patch only defines a minimum but most common set of branch types.
> >
> > PERF_BR_UNKNOWN         : unknown
> > PERF_BR_COND            ：conditional
> > PERF_BR_UNCOND          : unconditional
> > PERF_BR_IND             : indirect
> > PERF_BR_CALL            : function call
> > PERF_BR_IND_CALL        : indirect function call
> > PERF_BR_RET             : function return
> > PERF_BR_SYSCALL         : syscall
> > PERF_BR_SYSRET          : syscall return
> > PERF_BR_COND_CALL       : conditional function call
> > PERF_BR_COND_RET        : conditional function return
> >
> > The patch also adds a new field type (4 bits) in perf_branch_entry
> > to record the branch type.
> >
> > Since the disassembling of branch instruction needs some overhead,
> > a new PERF_SAMPLE_BRANCH_TYPE_SAVE is introduced to indicate if it
> > needs to disassemble the branch instruction and record the branch
> > type.
> >
> > Change log
> > ----------
> > v10: Not changed.
> >
> > v9: Not changed.
> >
> > v8: Change PERF_BR_NONE to PERF_BR_UNKNOWN.
> >     No other change.
> 
> I acked v8, so you could have retained my ack. Here it is again:
> 
> Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)

Ok, collecting acks from you, Jiri and PeterZ, will try to get this
upstreamed soon.

- Arnaldo