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

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Date:   Fri, 29 Jan 2021 08:42:21 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
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



On 1/28/2021 8:43 PM, Arnaldo Carvalho de Melo wrote:
> 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
> 

Thanks Arnaldo!

OK, let me try to improve the intlist.

Thanks
Jin Yao