Date: Wed, 21 May 2008 20:17:51 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-stable@FreeBSD.ORG, unga888@yahoo.com Subject: Re: sched_ule performance on single CPU Message-ID: <200805211817.m4LIHpbd024904@lurza.secnetix.de> In-Reply-To: <438315.78030.qm@web57004.mail.re3.yahoo.com>
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Sorry for the late reply, but I think there's a technical detail that should be mentioned ... Unga <unga888@yahoo.com> wrote: > My earlier test shows processes in the normal category > can starve processes in real-time category. That's > alarming. It should be get fixed. Note that FreeBSD does not support "hard real time" processing. Strictly speaking no OS does that on PC standard hardware. FreeBSD's idprio/rtprio implementation only affects the decisions of the scheduler, i.e. the assignment of CPU time slices to processes. However, there are other resources beside CPU that influence the execution of processes. For example disk I/O. In other words, if an idle-prio process performs a lot of disk accesses, it creates an I/O bottleneck, and even realtime-prio processes will have to wait because the hardware (disk) is blocked. This problem can be alleviated by using faster and better hardware, e.g. a SCSI RAID-0 disk subsystem or whatever. Besides, for professional audio recording you will also need professional audio hardware (which should include its own buffer memory, among other things), not a consumer card or an el'cheapo USB dongle. Best regards Oliver PS: My notebook at home (Pentium-M, UP, 3 years old) works very well with FreeBSD/i386 RELENG_7 + SCHED_ULE. -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing." -- Mother Teresa
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