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Message-ID: <3efb10970801311136y12670f12x6e4fdd44de3677b9@mail.gmail.com>
Date: Thu, 31 Jan 2008 20:36:25 +0100
From: "Remy Bohmer" <linux@bohmer.net>
To: "Haavard Skinnemoen" <hskinnemoen@atmel.com>
Subject: Re: [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler
Cc: michael <trimarchi@gandalf.sssup.it>, fabio@gandalf.sssup.it,
       "Andrew Victor" <linux@maxim.org.za>,
       "Chip Coldwell" <coldwell@redhat.com>,
       "Marc Pignat" <marc.pignat@hevs.ch>,
       "David Brownell" <david-b@pacbell.net>, linux-kernel@vger.kernel.org,
       "Alan Cox" <alan@lxorguk.ukuu.org.uk>
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Hello Haavard,

> It seems to be very sensitive to network traffic though...could it have
> something to do with softirq scheduling? Could you try the patch below
> and see if you can trigger the error message?

Funny that you mention this.
The largest latencies I currently have on RT (and rm9200) occur when
using a telnet session or NFS filesystems, thus while using network.
The impact on hardware Interrupt latencies are limited (<85us), so the
interrupt handler should still be able to keep up the receive buffer,
but context switches between threads can stall for a longer time under
some conditions.
A long shot, but can it be that the ringbuffer overflows, and that
therefor characters are lost?


Kind Regards,

Remy
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