There is the hwlat program in rt-tools .... and debugfs/tracing which will give max latencies.
Note that the OSADL values are not from userspace ! Atleast the way I read ther documentation on the testing, so from userspace there will be a 'little' more jitter/latency . Here is some on the latency tracer, it's a beauty ! :-D http://lwn.net/Articles/97811/ Often you end up in drivers for specific hardware , but for tuning of the platform it's the same for all systems, ( RTAI/xenomai/rt-preempt ) ie. black-magick ! Search on linux kernel latency tracer and you will find a lot. My short list is disable power save, set rational swappiness, be sure to set rt-priorities ! / regards, Lars Segerlund. 2012/10/15 Kent A. Reed <kentallanr...@gmail.com>: > On 10/11/2012 2:12 AM, Lars Segerlund wrote: >> Me thinks latest preempt-rt is preferable .... fx. there is a patch >> that shaves 100 uS of the arm worstcase ... ( in the tty driver of all >> places ) ... >> >> The biggest problem with preempt-rt is the tuning, to get good >> results we should do a little eality check ... ( ie. disable all power >> save , and so ) > > Before I went on holiday I had followed in Charles' footsteps to build > preempt-rt kernels and test them on several Intel and AMD boards. The > latencies I got weren't very good (although not wildly out of line with > oasdl postings) and certainly not as good as Charles got with his > particular boards. > > So far, I have been utterly unable to make any substantial difference > "tuning". Does a systematic tuning process exist? So far all I have is > the usual laundry list of "try this..." suggestions. > > Regards, > Kent > > > ------------------------------------------------------------------------------ > Don't let slow site performance ruin your business. Deploy New Relic APM > Deploy New Relic app performance management and know exactly > what is happening inside your Ruby, Python, PHP, Java, and .NET app > Try New Relic at no cost today and get our sweet Data Nerd shirt too! > http://p.sf.net/sfu/newrelic-dev2dev > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Don't let slow site performance ruin your business. Deploy New Relic APM Deploy New Relic app performance management and know exactly what is happening inside your Ruby, Python, PHP, Java, and .NET app Try New Relic at no cost today and get our sweet Data Nerd shirt too! http://p.sf.net/sfu/newrelic-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
