Messages in this thread | | | Date | Tue, 14 Mar 2006 16:59:51 -0500 | From | Shailabh Nagar <> | Subject | Re: [Patch 0/9] Per-task delay accounting |
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Greg KH wrote:
>On Tue, Mar 14, 2006 at 03:49:16PM -0500, Shailabh Nagar wrote: > > >>Greg KH wrote: >> >> >> >>>On Mon, Mar 13, 2006 at 07:40:34PM -0500, Shailabh Nagar wrote: >>> >>> >>> >>> >>>>This is the next iteration of the delay accounting patches >>>>last posted at >>>> http://www.ussg.iu.edu/hypermail/linux/kernel/0602.3/0893.html >>>> >>>> >>>> >>>> >>>Do you have any benchmark numbers with this patch applied and with it >>>not applied? >>> >>> >>> >>None yet. Wanted to iron out the collection/utility aspects a bit before >>going into >>the performance impact. >> >>But this seems as good a time as any to collect some stats >>using the usual suspects lmbench, kernbench, hackbench etc. >> >> >> >>>Last I heard it was a measurable decrease for some >>>"important" benchmark results... >>> >>> >>> >>> >>Might have been from an older iteration where schedstats was fully enabled. >>But no point speculating....will run with this set of patches and see >>what shakes out. >> >>One point about the overhead is that it depends on the frequency with >>which data is >>collected. So a proper test would probably be a comparison of a >>non-patched kernel >>with >>a) patches applied but delay accounting not turned on at boot i.e. cost >>of the checks >>b) delay accounting turned on but not being read >> >> > >This is probably the most important one, as that is what distros will be >looking at. They will have to enable the option, but will not "turn it >on". > > I guess you meant a), not b) but yes, will run them in all these modes.
> > >>c) delay accounting turned on and data read for all tasks at some >>"reasonable" rate >> >>Will that be good ? Other suggestions welcome. >> >> > >How about real benchmarks? The ones that the big companies look at? I >know you have access to them :) > > Hmm...though you also know, from working for some "big company", that it might take a while to get such data since one has to stand in queue :-) I'll try, and also explore the OSDL STP's DBT tests.
Thanks, Shailabh
>thanks, > >greg k-h > >
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