Re: 2.6.11, IDE: Strange scheduling behaviour: high-pri RT process not scheduled?

From: Bartlomiej Zolnierkiewicz
Date: Wed Mar 30 2005 - 07:08:14 EST


On Wed, 30 Mar 2005 13:52:05 +0200, kus Kusche Klaus <kus@xxxxxxxx> wrote:

> However, things break seriously when exercising the CF card in parallel
> (e.g. with a dd if=/dev/hda of=/dev/null):
>
> * The rtc *interrupt handler* is delayed for up to 250 *micro*seconds.
> This is very bad for my purpose, but easy to explain: It is roughly the
> time needed to transfer 512 Bytes from a CF card which can transfer 2
> Mbyte/sec, and obviously, the CPU blocks all interrupts while making pio
>
> transfers. (Why? Is this really necessary?)
>
> (I know because I instrumented the rtc irq handler with rdtscl(), too)

hdparm -u1 /dev/hda

should help
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