Date: Fri, 10 Sep 2004 09:31:23 -0400 From: Suleiman Souhlal <ssouhlal@FreeBSD.org> To: Suleiman Souhlal <ssouhlal@FreeBSD.org> Cc: =?ISO-8859-1?Q?Markus_H=E4stbacka?= <midian@ihme.org> Subject: Re: Sound performance problems in FreeBSD Message-ID: <B586FC4E-032D-11D9-835C-000A95C4D7BC@FreeBSD.org> In-Reply-To: <24D02CEA-022C-11D9-870B-000A95C4D7BC@FreeBSD.org> References: <20040905124526.F15143@midi.ihme.net> <24D02CEA-022C-11D9-870B-000A95C4D7BC@FreeBSD.org>
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Hi, > FYI, after a few IRC discussions with Markus, we've discovered that > turning off the memory part of Gnome's System Monitor applet, would > get rid of the skips. I believe the problem is that both sysctl and > the sound drivers are Giant-locked, and so there is some contention. > An easy way to reproduce these > skips is to run `while true; do sysctl vm.vmtotal; done`, while > playing an mp3. In case you are interested, we've confirmed that Giant contention is the problem: Applying the hack at http://people.freebsd.org/~ssouhlal/giantless-sysctl.diff , which removes Giant from sysctl, seems to stop the skips when running the above command. Of course, it doesn't prevent skips from happening during heavy file operation, which would probably require VFS locking (or of course, locking the sound drivers, which is probably easier), and maybe, a better disk scheduler. -- Suleiman Souhlal | ssouhlal@vt.edu The FreeBSD Project | ssouhlal@FreeBSD.org
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