Date: Thu, 22 Feb 2001 13:52:28 +0900 From: Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp> To: "Cameron Grant" <gandalf@vilnya.demon.co.uk>, John Baldwin <jhb@FreeBSD.org> Cc: Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>, current@FreeBSD.org Subject: MP-safe midi(4) and sequencer callout priority Message-ID: <vmu25nfhf7.wl@rina.r.dl.itc.u-tokyo.ac.jp>
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The patch at http://people.FreeBSD.org/~tanimura/patches/midimutex.diff.gz makes midi(4) MP-safe. With this patch, my kernel with WITNESS and INVARIANTS plays my favorite midi tunes just fine, except that the callout used by the midi sequencer gets delayed under a heavy load. As the sequencer uses callout in order to wait until the next midi message is ready to be transmitted, the callout should run at PI_AV so that a tune will not sound messy. John, have you got any plan to modify the priority of a callout? Cameron, as pcm(4) interacts with few of the other subsystems in the kernel like midi(4), why don't you start making pcm(4) MP-safe? Multimedia devices should benefit very much from kernel execution in parallel. The only one thing to note is to not access a device in parallel to mess it up. We have to add a mutex to a device and share the mutex between the pcm part and the midi part of the driver. Could you please let me know when pcm(4) gets MP-safe, and we will see how we can share device mutexes between pcm(4) and midi(4). -- Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp> <tanimura@FreeBSD.org> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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