linux-kernel - Re: [PATCH 1/2] perf script: Support filtering by hex address

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Date:   Thu, 28 Jan 2021 09:43:10 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     "Jin, Yao" <yao.jin@...ux.intel.com>
Cc:     Jiri Olsa <jolsa@...hat.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 1/2] perf script: Support filtering by hex address

Em Thu, Jan 28, 2021 at 11:31:26AM +0800, Jin, Yao escreveu:
> On 1/28/2021 7:13 AM, Jiri Olsa wrote:
> > > @@ -709,6 +725,26 @@ int machine__resolve(struct machine *machine, struct addr_location *al,
> > >   			ret = strlist__has_entry(symbol_conf.sym_list, al_addr_str);
> > >   		}
> > > +		if (!ret && al->map) {
> > > +			snprintf(al_addr_str, sz, "0x%"PRIx64,
> > > +				al->map->unmap_ip(al->map, al->addr));
> > > +			ret = strlist__has_entry(symbol_conf.sym_list,
> > > +						 al_addr_str);
> > > +			if (!ret) {
> > > +				/* Check for hex without "0x" prefix */
> > > +				snprintf(al_addr_str, sz, "%"PRIx64,
> > > +					al->map->unmap_ip(al->map, al->addr));
> > > +				ret = strlist__has_entry(symbol_conf.sym_list,
> > > +							 al_addr_str);
> > > +			}
> > that seems tricky.. what if user specify more leading zeros,
> > I think it'd be better to search intlist instead

> > we could move all 'address' entries from sym_list to
> > new intlist (in symbol__init) and use it for this search

> intlist now only supports 'int' type.

> I'm considering to use 'long' to replace original 'int' in struct int_node.

> struct int_node {
> 	struct rb_node rb_node;
> -	int i;
> +	long i;
> 	void *priv;
> };

> On 32 bits platform, sizeof(long) is 4, and on 64 bits platform,
> sizeof(long) is 8. So that should be OK for storing the values such as
> pid/tid and address.

> I'm not very clear why currently it uses 'int' for i in struct int_node,
> maybe something I don't understand correctly. Please correct me if my
> understanding is wrong.

I think its ok to make it a long, it won't even enlarge the struct
because:

[acme@...co pahole]$ pahole -C int_node ~/bin/perf
struct int_node {
	struct rb_node             rb_node __attribute__((__aligned__(8))); /*     0    24 */
	int                        i;                                       /*    24     4 */

	/* XXX 4 bytes hole, try to pack */

	void *                     priv;                                    /*    32     8 */

	/* size: 40, cachelines: 1, members: 3 */
	/* sum members: 36, holes: 1, sum holes: 4 */
	/* forced alignments: 1 */
	/* last cacheline: 40 bytes */
} __attribute__((__aligned__(8)));
[acme@...co pahole]$

:-)

- Arnaldo