linux-kernel - Re: [PATCH 2/5] perf script: extend db-export api to include callchains for samples

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Date:	Thu, 28 Apr 2016 01:36:50 -0700
From:	Chris Phlipot <cphlipot0@...il.com>
To:	Adrian Hunter <adrian.hunter@...el.com>, acme@...nel.org,
	mingo@...hat.com, peterz@...radead.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] perf script: extend db-export api to include
 callchains for samples

Hi Adrian,

I have just resubmitted these changes as a new patch set, which I believe
should address most of your concerns. Please review the new patch set
instead of continuing with this one.

https://lkml.org/lkml/2016/4/28/75

Thanks,
Chris

On 04/22/2016 09:41 PM, Chris Phlipot wrote:
>
>
> On 04/22/2016 12:56 AM, Adrian Hunter wrote:
>> The call_paths table already has symbol_id which belongs uniquely to 
>> a DSO,
>> so why do we need dso_id as well?
> If the symbol_id is 0 because the IP could not be resolved to a 
> symbol, this is not necessarily a valid assumption. Without a dso_id 
> in the call_paths table, it is not possible to resolve the dso when 
> symbol information is missing. the db_export api currently does not 
> have enough information to match a DSO with an IP.
>
> It is often useful to still have the call path associated with a DSO 
> even if there is no symbol, which i why i recommend keeping the dso_id 
> in the call_paths table.
>> Why do you need a callback?  Seems like the only thing you need from
>> thread-stack.c is the call path tree.  You could move that to its own 
>> .c/.h
>> files and then process the call chain in db-export.c
> My original intent was to reuse existing code with minimal changes and 
> conform the existing design patterns they used. Thread-stack.c, for 
> example, currently uses a callback to populate the call_return table, 
> so I used a callback as well to populate the call_path table.
>
> I am open to making this change if it is believed it will result in a 
> cleaner implementation.
>>
>> Also a list of changes like the one above heavily implies you are not
>> obeying the one patch == one change rule.  Please try to make patches 
>> that
>> only do one thing and also run checkpatch.
> While i can split this into a few smaller patches there is only really 
> justification for applying all of them all together. If this is still 
> preferred i can resubmit this in smaller parts.
>>
>> If you don't mind, I'll let you respond to my comments before I 
>> comment on
>> any other patches.
>>
> Let me know if you have any additional comments.
>
> Thanks,
> Chris