Re: [PATCH 4/4] tracing, page-allocator: Add a postprocessing script for page-allocator-related ftrace events

[Rik van Riel <riel@redhat.com>]

Andrew Morton wrote:
> On Tue,  4 Aug 2009 19:12:26 +0100 Mel Gorman <mel@csn.ul.ie> wrote:
> 
>> This patch adds a simple post-processing script for the page-allocator-related
>> trace events. It can be used to give an indication of who the most
>> allocator-intensive processes are and how often the zone lock was taken
>> during the tracing period. Example output looks like
>>
>> find-2840
>>  o pages allocd            = 1877
>>  o pages allocd under lock = 1817
>>  o pages freed directly    = 9
>>  o pcpu refills            = 1078
>>  o migrate fallbacks       = 48
>>    - fragmentation causing = 48
>>      - severe              = 46
>>      - moderate            = 2
>>    - changed migratetype   = 7
> 
> The usual way of accumulating and presenting such measurements is via
> /proc/vmstat.  How do we justify adding a completely new and different
> way of doing something which we already do?

Mel's tracing is more akin to BSD process accounting,
where these statistics are kept on a per-process basis.

Nothing in /proc allows us to see statistics on a per
process basis on process exit.

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