[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: Serial Latency Issues, Baud Rate Affects Buffering



>I'll give 2.4.22 a shot.

>Is the 2.4.22 on your website different from the official sources from 
>kernel.org?

On the website we have a patch compared to 2.4.22. The patch contains
e.g. a newer serial port driver. In 2.4.25 the official sources will
contain the serial driver patches. Takes a while to get our stuff
into the official trees.

/Mikael

PS. As Johan already mentioned you can never trust that you will get 
7 characters at each iteration. User space has no guarantees what
so ever. DS.

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com">mailto:owner-dev-etrax@xxxxxxx.com] On
Behalf Of Eric Sorton
Sent: Friday, January 09, 2004 9:16 PM
To: Johan Adolfsson; dev-etrax
Subject: Re: Serial Latency Issues, Baud Rate Affects Buffering


On Friday 09 January 2004 14:53, you wrote:
> Note the "to see if we should force DMA to flush" in the help text,
> which make it consistent with the code - "we should" is only true
> if no data has been received since the last check.

Subtle.

> You could modify force_eop_if_needed() I guess, but I wouldn't
recommend
> it.

I had already tested adding FLUSH_EOP() to force_eop_if_needed() prior
to 
receiveing this message.  It definately improved the latency :-)

Is the only drawback performance?  Or am I going to have "other"
problems?

> Not any more, it's implemented in the 2.4.22 kernel along with other
> improvements.

I'll give 2.4.22 a shot.

Is the 2.4.22 on your website different from the official sources from 
kernel.org?

Thanks for your help,

Eric

-- 
Eric Sorton
Senior Member Research Staff
Institute for Scientific Research (ISR), Inc.
119 Roush Circle
Industrial Park Road
Fairmont, WV  26554
Email: esorton@xxxxxxx.org
URL: http://www.isrparc.org
Voice: 304-368-9300 x219
FAX: 304-534-4106