Date: Sat, 6 Jun 1998 13:12:49 -0500 (EST) From: "John S. Dyson" <dyson@FreeBSD.ORG> To: straka@home.com (Richard S. Straka) Cc: bde@zeta.org.au, current@FreeBSD.ORG Subject: Re: strange behavior with signal latencies Message-ID: <199806061812.NAA04735@dyson.iquest.net> In-Reply-To: <3577F59D.983C4EE4@home.com> from "Richard S. Straka" at "Jun 5, 98 06:41:49 am"
next in thread | previous in thread | raw e-mail | index | archive | help
Richard S. Straka said: > > BTW, these latancy times really go out the window (10+ms ) when > the system is loaded with disk writing or network activity. I have performed > similar tests on an Ultra 30 box running Solaris 2.6. Even under extreme > loading, the latencies stay below 1ms (its no VxWorks, but it ain't bad for > soft > realtime). It appears that Solaris does very little work in hardware > interrupts, > defering work to preemtable kernel threads which are under control of the > scheduler. They offer a realtime scheduling class which has higher priority > than their system scheduling class. The amount of work we currently do in > FreeBSD in hardware and software interrupts coupled with the > non-preemtable nature of kernel activity precludes us from doing even > soft realtime work. > I would *love* to be able to support such a scheme, without a performance hit. Where an improvement (in overall performance) might be seen is in the SMP world, or where you need realtime. We will soon have much of the low level support for such a scheme (except for the interrupt handling methods.) I can guess that *someday* it will be reasonable for us to do that, but we tend to be evolutionary rather than revolutionary in our movements. I have been thinking in the background of a reasonable realtime scheme. -- John | Never try to teach a pig to sing, dyson@freebsd.org | it just makes you look stupid, jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199806061812.NAA04735>