Re: [PATCH] perf: do not flush maps on COMM for perf report

[David Ahern <dsahern@gmail.com>]

On 8/22/12 12:16 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Aug 22, 2012 at 10:56:13AM -0600, David Ahern escreveu:
>> On 8/22/12 10:29 AM, Arnaldo Carvalho de Melo wrote:
>>> Adding the EXEC event, ditto. And I agree that while adding it we want
>>> to do 1/2 as pre-requisite.
>>
>> maps should not be flushed on a COMM event, so that was a mistake.
>> Given that what new information does an EXEC event provide? Same
>> process id. A COMM event is generated on an exec, so the name change
>> happens. Mappings are dropped prior to that - and there is no unmap
>> event. That seems to be a missing piece. Maps are added which is
>> handled by MMAP events. After that why is an exec event relevant?
>
> Please read the original discussion about it:
>
> https://lkml.org/lkml/2012/2/13/545

I do recall that discussion (and re-read just now). If maps are not 
flushed on a rename (and they should not be), then I still do not 
understand what information is conveyed by an exec event? It's not a new 
process or new map and the name change is already handled by a comm event.

David