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ShabbyX / RTAI

(NO LONGER MAINTAINED) Clone of RTAI from https://www.rtai.org
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Unused drivers causing latency? #19

Closed ShabbyX closed 10 years ago

ShabbyX commented 10 years ago

@iw2lsi

First off, thanks for the pages!

I have a question, though. On the kernel configuration page, you mentioned that:

[removing unused drivers] will reduce your compilation time and, in my experience, your latency.

May I ask how is that? I would expect unused drivers to simply take up disk-space. Are you sure you acheived lower latency just by removing the unused drivers.

ShabbyX commented 10 years ago

Actually another theory could be that some config that was force-selected due to presence of some driver was automatically deselected after disabling it. It would be interesting to see if that's the case and if so, what was the troubling configuration.

iw2lsi commented 10 years ago

Hello Shabby...

sorry... I made a mistake... that should be "removing all unused features"...

In my experience, removing all unused features (ISDN, Firewall stack, various networks protocol, unused filesystems, drivers for hardware I don't have etc etc) reduce the latency of about 1-2 us.

the real surprise for me is that switching from one console to another as fast as possible, increase the latency even after hours of work in heavy load conditions... don't know why.

   Giampaolo

     Giampaolo

2014-09-29 17:08 GMT+02:00 Shahbaz Youssefi notifications@github.com:

Actually another theory could be that some config that was force-selected due to presence of some driver was automatically deselected after disabling it. It would be interesting to see if that's the case and if so, what was the troubling configuration.

Reply to this email directly or view it on GitHub https://github.com/ShabbyX/RTAI/issues/19#issuecomment-57175098.

ShabbyX commented 10 years ago

@iw2lsi Ah I see, of course.

It puzzles me too, why changing TTYs should be worse than all those other things you mentioned. Perhaps something related to changing graphics card modes or something.

Anyway, thanks again.