From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: From: "Russ Cox" To: 9fans@cse.psu.edu Subject: Re: [9fans] system responsiveness MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Thu, 2 May 2002 11:11:47 -0400 Topicbox-Message-UUID: 84b3f888-eaca-11e9-9e20-41e7f4b1d025 > I don't recall the details, but while I was playing with > the scheduler last fall Russ and I found that there was a > bug with assigning priorities. Under load the scheduler > was a real dog; I think Russ subsequently fixed it. Doing Presotto put some tweaks in for me. The processes move around dynamically (between priority levels) a bit more now. My particular test case was an mp3 encoder, which yielded the processor to go to disk just often enough that it wasn't being penalized for using so much CPU. The scheduler is more responsive now to long-term CPU hogs that occasionally schedule, so that background tasks like mp3enc won't hurt your interactive performance as much. > so made the system noticeably snappier. I also ran into > some problems with what appeared to be lost clock > interrupts, but never had the time to track things down > completely. This is a really cool bug. The system would just stop scheduling other processes, but if you moved the mouse around that would generate enough interrupts that the preemptive scheduler would go into effect and get you going. Stop the moving the mouse, stop making progress. We never found it, and all that has been rewritten recently so maybe it got fixed inadvertently. Russ