Date: Thu, 30 Oct 1997 23:06:45 -0500 (EST) From: Chuck Robey <chuckr@glue.umd.edu> To: "Jamil J. Weatherbee" <jamil@trojanhorse.ml.org> Cc: hackers@FreeBSD.ORG Subject: Re: Kernel Preemption Message-ID: <Pine.BSF.3.96.971030230554.10708A-100000@picnic.mat.net> In-Reply-To: <Pine.BSF.3.96.971030202542.275A-100000@trojanhorse.ml.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 30 Oct 1997, Jamil J. Weatherbee wrote: > > What is being done in the area of making the kernel preemptable. I had > some issues recently because of the size of blocks that some drivers can > read/write and the length of time it might take them could be prehibitive, > for instance something that just outb()'s a block, which i have discovered > can e as big as a 1/2 megabyte. So in general if this is a long time you > have a problem with interactive response. > > For instance using rtprio 20 maplay x.mp3 to run an mpeg3 file which > consumes about 40% cpu time for me usually runs quite nicely (no popping > etc). With the exception of a very rare pop under heavy disk load, such as > a find on the whole drive. In fact I often do make worlds and run mpeg > 3's without a glitch. This should also apply to those interested in > burning cd roms. > > A regualr user can log on while youre doing these things and ruin your > whole day via: > > cat /dev/urandom > /dev/null Can't you just use nice(1) to raise the priority of maplay? > > Now you have a real problem with running any "realtime" processes. > What steps can be taken in the freebsd kernel to remedy this sort of > thing. > > I am not saying that urandom should not be in the kernel, just that a > better method is needed of doing cpu or time intensive tasks in the > kernel. We cannot always depend on ever read/write operation being > instantaneous, even if our driver is the most holy of holy interrupt > driven stuff. There is no good reason you shouldn't be able to do an > intensive calculation in the kernel. > > Would whatever SMP stuff is being worked on apply here, even without > multiple processors? > > > > > > > ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@glue.umd.edu | communications topic, C programming, and Unix. 213 Lakeside Drive Apt T-1 | Greenbelt, MD 20770 | I run Journey2 and picnic, both FreeBSD (301) 220-2114 | version 3.0 current -- and great FUN! ----------------------------+-----------------------------------------------
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.96.971030230554.10708A-100000>