Re: [PATCH v9 2/7] perf/x86/intel: Record branch type

[Jin, Yao]

On 7/17/2017 4:11 PM, Jiri Olsa wrote:
> On Mon, Jul 17, 2017 at 07:06:38PM +0800, Jin Yao wrote:
>
> SNIP
>
> > +#define X86_BR_TYPE_MAP_MAX	16
> > +
> > +static int
> > +common_branch_type(int type)
> > +{
> > +	int i;
> > +	const int branch_map[X86_BR_TYPE_MAP_MAX] = {
> > +		PERF_BR_CALL,		/* X86_BR_CALL */
> > +		PERF_BR_RET,		/* X86_BR_RET */
> > +		PERF_BR_SYSCALL,	/* X86_BR_SYSCALL */
> > +		PERF_BR_SYSRET,		/* X86_BR_SYSRET */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_INT */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_IRET */
> > +		PERF_BR_COND,		/* X86_BR_JCC */
> > +		PERF_BR_UNCOND,		/* X86_BR_JMP */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_IRQ */
> > +		PERF_BR_IND_CALL,	/* X86_BR_IND_CALL */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_ABORT */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_IN_TX */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_NO_TX */
> > +		PERF_BR_CALL,		/* X86_BR_ZERO_CALL */
> > +		PERF_BR_UNKNOWN,	/* X86_BR_CALL_STACK */
> > +		PERF_BR_IND,		/* X86_BR_IND_JMP */
> > +	};
> should the branch_map array be static? having it on stack makes
> the compiler to create it every time we call the function
>
> jirka

OK, agree to let branch_map array be static. I will add this in v10.

I'm also waiting for Peter's review comments for this patch update.

Thanks
Jin Yao

> > +
> > +	type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */
> > +
> > +	if (type) {
> > +		i = __ffs(type);
> > +		if (i < X86_BR_TYPE_MAP_MAX)
> > +			return branch_map[i];
> > +	}
> > +
> > +	return PERF_BR_UNKNOWN;
> > +}
> > +
> >   /*
> >    * implement actual branch filter based on user demand.
> >    * Hardware may not exactly satisfy that request, thus
> > @@ -942,7 +987,8 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
> >   	bool compress = false;
> >   
> >   	/* if sampling all branches, then nothing to filter */
> > -	if ((br_sel & X86_BR_ALL) == X86_BR_ALL)
> > +	if (((br_sel & X86_BR_ALL) == X86_BR_ALL) &&
> > +	    ((br_sel & X86_BR_TYPE_SAVE) != X86_BR_TYPE_SAVE))
> >   		return;
> >   
> >   	for (i = 0; i < cpuc->lbr_stack.nr; i++) {
> > @@ -963,6 +1009,9 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
> >   			cpuc->lbr_entries[i].from = 0;
> >   			compress = true;
> >   		}
> > +
> > +		if ((br_sel & X86_BR_TYPE_SAVE) == X86_BR_TYPE_SAVE)
> > +			cpuc->lbr_entries[i].type = common_branch_type(type);
> >   	}
> >   
> >   	if (!compress)
> > --
> > 2.7.4