[sorry for the cross posting] Over the last couple of months I have been seeing emails on the the darwin developement lists from various developers regarding latency in Darwin. It appears that they are finding some issue with latency when using the normal IOKit methods. I personally never did get a clear understand of what was causing the latency but it seems to be driving people to do more work at direct interrupt time (more code going into IOFilterInterruptEventSource::Filter) or for some skipping the use of the IOKit provided workloops. I personally see this as a dangerous trend for two main reasons (more exist)... 1) Apple may have a issue in the kernel that needs to be fixed or improved and people are coding around it instead of working with Apple to resolved it. 2) More people doing stuff at direct interrupt time is going to cause worse behavior for those following the generally accepted/specified methods (using work loops and doing stuff at indirect interrupt or better yet doing it in worker a thread). Direct interrupt time holds up the entire system (I believe all processors). So spending much time here can impact total system performance. If we have people heading down this path we are going to have problems IMHO. Basically if more people start hogging the system then others may be forced to do the same. Please only do stuff at direct interrupt time if no other way exists to achieve what you need to do. AND.... do this ONLY after working with Apple and/or the Darwin community to isolate the issue(s) you maybe experiencing and if they can find no alternatives. -Shawn _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.