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Message-ID: <8bd0f97a0906030103i64bc1a9duc5aeaea7bd3f8365@mail.gmail.com>
Date:	Wed, 3 Jun 2009 04:03:46 -0400
From:	Mike Frysinger <vapier.adi@...il.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Mike Frysinger <vapier@...too.org>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Cliff Cai <cliff.cai@...log.com>,
	Bryan Wu <cooloney@...nel.org>
Subject: Re: [PATCH 04/11] Blackfin SPORT UART: fix overrun errors

On Tue, Jun 2, 2009 at 05:00, Alan Cox wrote:
> On Tue,  2 Jun 2009 03:11:33 -0400 Mike Frysinger wrote:
>> From: Cliff Cai <cliff.cai@...log.com>
>>
>> Push the ty_flip_buffer_push() call from the IRQ handler to a timer so as
>> to improve performance and decrease likelihood of overruns.
>
> This should have no effect on a modern kernel.

well, we wouldnt be making changes if we werent seeing data overruns today

> There is 64K of queueing between you and the ldisc nowdays.

i dont think that really matters ... we do too much work in the
interrupt and so we miss new data

> Furthermore unless you set tty->low_latency the kernel already basically
> does this aggregation for you as the buffer push queues stuff for the ldisc
> to wake up and process.

i guess we could try setting the low_latency bool instead and see if
that fixes things
-mike
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