From: Vojtech Pavlik <vojtech@suse.cz>
To: David Wuertele <dave-gnus@bfnet.com>
Cc: linux-ide@vger.kernel.org
Subject: Re: Compact Flash PIO 4 tuning
Date: Tue, 6 May 2003 07:47:34 +0200 [thread overview]
Message-ID: <20030506074734.C2287@ucw.cz> (raw)
In-Reply-To: <m3llxkyjxs.fsf@bfnet.com>; from dave-gnus@bfnet.com on Mon, May 05, 2003 at 05:53:35PM -0700
On Mon, May 05, 2003 at 05:53:35PM -0700, David Wuertele wrote:
> Howdy,
>
> I'm working on an embedded system that has a CF card on the IDE bus.
> The CF spec only allows PIO mode, and my card can do PIO 4. However,
> when I try to stream data from this card into memory at 2 MBytes per
> second, it pegs the CPU at 100%. This is ruining the performance of
> my application, which has to process this data in real time.
>
> I realize that PIO 4 requires CPU involvement, but are there ways I
> can tune the kernel for copying large files to memory, so that my
> application doesn't get starved of CPU?
If you use the full bandwidth of the PIO device, you use 100% CPU.
That's it and there's no way around. You can check that the IDE/CF
interface is set to PIO4 and that under Linux you have IRQ unmasking
enabled, those two will help, though the first statement is still
valid.
--
Vojtech Pavlik
SuSE Labs, SuSE CR
prev parent reply other threads:[~2003-05-06 5:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-06 0:53 Compact Flash PIO 4 tuning David Wuertele
2003-05-06 5:47 ` Vojtech Pavlik [this message]
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