Measuring semaphore contention times with markers

[Vara Prasad]

Mike Mason wrote:

> Frank Ch. Eigler wrote:
>
>> Mike Mason <mmlnx@us.ibm.com> writes:
>>
>>> FWIW... Here's a simple example of using markers to measure
>>> semaphore contention times.  I don't claim that it's complete or
>>> efficient, just an example of an area where markers are useful.
>>
>>
>> Indeed.  (The equivalent systemtap script should be more compact.)
>>
>> In order for upstream to consider including these sorts of valuable
>> markers, they'll want to have some benchmarks.  Most important is
>> bound to be the overall slowdown caused by dormant markers, and second
>> would be the increase in code (.text) size.  Of lesser interest might
>> be the slowdown caused by a minimal marker handler that just returns.
>> Can you or someone else run some tests?
>
>
> OK, understood.  Has anyone benchmarked markers in general?  Any 
> suggestions on how to run a benchmark that will be acceptable to the 
> kernel community?
>
I understand the idea of bench marking these markers and it is a good 
thing to do but the goal i had in mind is to show ASAP how one would use 
markers along with probes to get valuable information that is not 
possible to get otherwise. My suggestion would be can we all provide the 
feedback to Mike in terms  of the code quality and cleanup so he can 
post ASAP in to the makers discussion thread in  LKML to justify value 
of them. We can do the bench marking later.

[snip]

bye,
Vara Prasad