linux-kernel - Re: [PATCH v7 1/7] perf/core: Define the common branch type classification

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Message-ID: <63ad127b-4a61-bf56-500f-98bca633998b@linux.intel.com>
Date:   Tue, 11 Jul 2017 20:29:21 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     acme@...nel.org, jolsa@...nel.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, mpe@...erman.id.au,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v7 1/7] perf/core: Define the common branch type
 classification



On 7/11/2017 8:06 PM, Peter Zijlstra wrote:
> On Tue, Jul 11, 2017 at 11:00:57PM +0800, Jin Yao wrote:
>> PERF_BR_NONE            : unknown
> I would suggest PERF_BR_UNKNOWN or PERF_BR_MISC, since PERF_BR_NONE
> reads like it wasn't a branch at all.

OK, I will change it to PERF_BR_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 (reserve 5 for future branch types)
> What's up with that 5 ? I can't see anything like that in the patch
> itself:

Sorry, I don't say this clearly.

We has defined 11 branch types (from PERF_BR_UNKNOWN to 
PERF_BR_COND_RET), so we can define 5 new types in future.

Thanks
Jin Yao

>> @@ -1024,7 +1048,8 @@ struct perf_branch_entry {
>>   		in_tx:1,    /* in transaction */
>>   		abort:1,    /* transaction abort */
>>   		cycles:16,  /* cycle count to last branch */
>> -		reserved:44;
>> +		type:4,     /* branch type */
>> +		reserved:40;
>>   };
>