[alsa-devel] ASoC: mmap or read/write?

Mike Looijmans mike.looijmans at topic.nl
Fri Oct 19 08:33:24 CEST 2012

Clemens ------------------------------ Message: 6 Date: Thu, 18 Oct 2012 
15:07:45 +0530 From: Prasant J <pj0585 at gmail.com> To: Clemens Ladisch 
<clemens at ladisch.de> Cc: alsa-devel at alsa-project.org Subject: Re: 
[alsa-devel] ASoC: mmap or read/write? Message-ID: 
<CAA2DH4v4DUxf5Qh79nehTPD+22v6XddzDrEMmnBu2eM8m4JXzg at mail.gmail.com> 
Content-Type: text/plain; charset=ISO-8859-1 On Thu, Oct 18, 2012 at 
2:39 PM, Clemens Ladisch <clemens at ladisch.de> wrote:
>> Prasant J wrote:
>>> I'm writing an alsa application for recording & playing 16 channel audio.
>>> The application is intended to run on an embedded platform & the
>>> resources are highly constrained.
>> Then I wonder how you manage to handle 16 channels.
>> What hardware is this?
> I'm working with Beaglebone (ARM Cortex-A8 720 MHz). (Currently
> failures are for 8 channels 32 bit / 16 bit, but our final target is
> 16 channels)
>>> My application is not performing well with read/write methods.
>> How much CPU usage?
> The CPU usage is around 35% (as seen in top)
> I have managed to get Audio capture working fine (after certain linux
> optimizations) but playback is giving under-runs (only when PLAYBACK &
> CAPTURE run together)
> I was wondering that changing access method to mmap (currently I'm
> using read/write) may give me some more CPU time.

You must be doing something wrong. I'm doing 32-bit, 16-channel input at 
51.2kHz on a OMAP-L138 (an ARM9 CPU at 450 MHz) under Linux and it's 
using no more than 25% CPU for that. Just using"arecord" for that.

(sorry for the company sig)

Met vriendelijke groet / kind regards,

Mike Looijmans

TOPIC Embedded Systems
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: (+31) – (0)499 - 33.69.79
Telefax: (+31) - (0)499 - 33.69.70
E-mail: mike.looijmans at topic.nl
Website: www.topic.nl

Dit e-mail bericht en de eventueel daarbij behorende bijlagen zijn uitsluitend bestemd voor de geadresseerde, zoals die blijkt uit het e-mail bericht en/of de bijlagen. Er kunnen gegevens met betrekking tot een derde instaan. Indien u als niet-geadresseerde dit bericht en de bijlagen ontvangt, terwijl u niet bevoegd of gemachtigd bent om dit bericht namens de geadresseerde te ontvangen, wordt u verzocht de afzender hierover direct te informeren en het e-mail bericht met de bijlagen te vernietigen. Ieder gebruik van de inhoud van het e-mail bericht, waaronder de daarbij behorende bijlagen, door een ander dan de geadresseerde is onrechtmatig jegens ons dan wel de eventueel in het e-mail bericht of de bijlagen voorkomende andere personen. TOPIC Embedded Systems is niet aansprakelijk voor enigerlei schade voortvloeiend uit het gebruik en/of acceptatie van dit e-mail bericht of de daarbij behorende bijlagen.

The contents of this message, as well as any enclosures, are addressed personally to, and thus solely intended for the addressee. They may contain information regarding a third party. A recipient who is neither the addressee, nor empowered to receive this message on behalf of the addressee, is kindly requested to immediately inform the sender of receipt, and to destroy the message and the enclosures. Any use of the contents of this message and/or the enclosures by any other person than the addressee or person who is empowered to receive this message, is illegal towards the sender and/or the aforementioned third party. TOPIC Embedded Systems is not  liable for any damage as a result of the use and/or acceptance of this message and as well as any enclosures.

More information about the Alsa-devel mailing list