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

[Mike Looijmans]

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.

Mike.
(sorry for the company sig)



Met vriendelijke groet / kind regards,

Mike Looijmans

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