Messages in this thread | | | Date | Thu, 10 May 2007 17:19:16 -0400 | From | Bill Davidsen <> | Subject | Re: Preempt of BKL and with tickless systems |
| |
Lee Revell wrote: > On 5/8/07, Bill Davidsen <davidsen@tmr.com> wrote: >> I think I have a reasonable grip on the voluntary and full preempt >> models, can anyone give me any wisdom on the preempt of the BKL? I know >> what it does, the question is where it might make a difference under >> normal loads. Define normal as servers and desktops. > > This was introduced by Ingo to solve a real problem that I found, > where some codepath would hold the BKL for long enough to introduce > excessive scheduling latencies - search list archive for details. But > I don't remember the code path (scrolling the FB console? VT > switching? reiser3? misc. ioctl()s?). Basically, taking the BKL > disabled preemption which caused long latencies. > > It's certainly possible that whatever issue led to this was solved in > another way since. > Anything is possible. I feel that using voluntary + bkl is probably good for most servers, forced preempt for desktop, although it really doesn't seem to do much beyond voluntary.
Thanks for the clarification.
-- Bill Davidsen <davidsen@tmr.com> "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |