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Re: Measuring semaphore contention times with markers


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


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