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Date:      Thu, 5 Jan 2006 12:35:44 +0800
From:      Ariff Abdullah <ariff@FreeBSD.org>
To:        Simon Barner <barner@FreeBSD.org>
Cc:        freebsd-multimedia@FreeBSD.org
Subject:   Re: Testing request: GIANT Free snd_solo(4)
Message-ID:  <20060105123544.73fb400a.ariff@FreeBSD.org>
In-Reply-To: <20060105032333.GA2865@zi025.glh.mhn.de>
References:  <20060104224705.3bb21deb.ariff@FreeBSD.org> <20060104151211.GB1128@zi025.glh.mhn.de> <20060104232933.7c915cff.ariff@FreeBSD.org> <20060104182532.GA1019@zi025.glh.mhn.de> <20060104191053.GA1037@zi025.glh.mhn.de> <20060105065827.65b27ac8.ariff@FreeBSD.org> <20060104235339.GA1222@zi025.glh.mhn.de> <20060105081205.04dfee19.ariff@FreeBSD.org> <20060105004404.GA2027@zi025.glh.mhn.de> <20060105100556.5cdb1043.ariff@FreeBSD.org> <20060105032333.GA2865@zi025.glh.mhn.de>

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[CC: freebsd-multimedia@]

On Thu, 5 Jan 2006 04:23:34 +0100
Simon Barner <barner@FreeBSD.org> wrote:
> > Great. Hopefully this would be out final test (sorry to bother you
> > too much):
> >=20
> >   http://people.freebsd.org/~ariff/test/solo.c
> >=20
> > .. and I'm assuming you're using default sound.c (since it's not
> > necessarily its fault).
> >=20
> > I've reworked a bit so the same file can be compiled both MPSAFE
> > and non-MPSAFE through the definition of ESS18XX_MPSAFE. I hope
> > you could test both conditions as well, especially regarding with
> > vchans auto creation through hw.snd.maxautovchans. You don't have
> > to reboot, simply using kenv(1) to set it, and kldload/unload.
>=20
> Results: When I do not fiddle around with any sysctls etc., it
> works as expected (MPSAFE w/ and w/0 vchans, non-MPSAFE w/ and w/0
> vchans)
>
Case closed :)

> >=20
> > My biggest concern is its DMA allignment. I've reduce its value to
> > see whether it should help, in any case.
> >=20
> > Few tricks to improve sound performance:
> >=20
> > 1) GIANT free
> > 2) PREEMPTION kernel
> > 3) using SCHED_ULE instead of SCHED_4BSD (and yes, SCHED_ULE)
> > 4) Reduce hw.snd.pcm.<unit>.buffersize as minimum as 4096. The
> > only
> >    place where this can be set is through kernel hints
> >    (/boot/device.hints) or using kenv(1) before loading the
> >    driver.
> > 5) Reduce hw.snd.targetirqrate , 16
> > 6) Avoid sharing IRQ with other peripherals. vmstat -i
> > 7) Enable DMA on all harddrives.
> > Optional:-
> > 8) Increase PCI Latency Timer, using pciconf. Sometimes it doesn't
> >    help at all.
> >=20
> > See whether 1-7 can help increase sound performance. A single
> > mozilla tarball sho
> > /usr/ports/sysutils/stress .
>=20
> Wow, nice list! You really should post it to multimedia@.
> I've followed it to the point (running SCHED_ULE now), and I
> verified that my sound card does not share any interupts, the
> harddrives all use UDMA33, and I tried all the suggested
> increasements and decreasments of all those knobs.
>=20
> Results: When I set hw.snd.pcm0.buffersize to 4096, the sound chokes
> (without any additional load). I took 8192 instead.
>=20
I'm assuming the default buffersize (16k) is fair enough.

> Untarring a huge tarball does not disturb the sound any more. The
> same applies for "stress --io n").
>=20
> But, if I simply copy my distfiles directory to /tmp, or if I run
> "stress --hdd 1", the sound get distorted again. As in my previous
> email, opening a big mbox has the same effect.
>
This will go into my TODO list.

> But I think the situation has improved, and there is an audible
> difference between the MPSAFE and the GIANT-locked driver when doing
> the benchmarks.
>=20
>
I'll commit this into -current straight away, MFC after a week
(depends on other people opinions).

Thanks.


--
Ariff Abdullah
FreeBSD

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