linux-kernel - Re: [PATCH v7 11/18] perf tools: add mem access sampling core support

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Message-ID: <20130327141425.GC1092@krava.brq.redhat.com>
Date:	Wed, 27 Mar 2013 15:14:25 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	ak@...ux.intel.com, acme@...hat.com, namhyung.kim@....com
Subject: Re: [PATCH v7 11/18] perf tools: add mem access sampling core support

On Thu, Jan 24, 2013 at 04:10:35PM +0100, Stephane Eranian wrote:

SNIP

>  
> +static void ip__resolve_data(struct machine *self, struct thread *thread,
> +			     u8 m,
> +			    struct addr_map_symbol *ams,
> +			    u64 addr)
> +{
> +	struct addr_location al;
> +
> +	memset(&al, 0, sizeof(al));
> +
> +	thread__find_addr_location(thread, self, m, MAP__VARIABLE, addr, &al,
> +				   NULL);
> +	ams->addr = addr;
> +	ams->al_addr = al.addr;
> +	ams->sym = al.sym;
> +	ams->map = al.map;
> +}
> +
> +struct mem_info *machine__resolve_mem(struct machine *self,
> +				      struct thread *thr,
> +				      struct perf_sample *sample,
> +				      u8 cpumode)
> +{
> +	struct mem_info *mi;
> +
> +	mi = calloc(1, sizeof(struct mem_info));
> +	if (!mi)
> +		return NULL;
> +
> +	ip__resolve_ams(self, thr, &mi->iaddr, sample->ip);
> +	ip__resolve_data(self, thr, cpumode, &mi->daddr, sample->addr);

question, should this be the other way around?  like:

	ip__resolve_ams(machine, thr, &mi->daddr, sample->addr);
	ip__resolve_data(machine, thr, cpumode, &mi->iaddr, sample->ip);

we have correct cpumode for sample->ip, but I think it's the
PEBS->dla (sample->addr) where we need to guess.. right?

that makes me think that we could probably use ip__resolve_data
for both.. hummm.. but we could access data cross the user/kernel
boundary, so cpumode would be different for ip and accessed data

thanks,
jirka
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