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SubjectRe: Unresponiveness of 2.4.16
On Tue, Nov 27, 2001 at 09:12:13AM -0800, Andrew Morton wrote:
> Ahmed Masud wrote:
> >
> > Just to add to the above something I've experienced:
> >
> > 2.4.12 - 2.4.14 on a number of AMD Athelon 900 with 256 MB
> > RAM doing serial I/O would miss data while any DISK writes would
> > occure.
>
> Two possibilities suggest themselves:
>
> - Interrupt latency. Last time I checked (a year ago), the worst-case
> interrupt latency of the IDE drivers was 80 microseconds on a 500MHz PII.
> That was with `hdparm -u 1'. That's pretty good.
>
> Could you please confirm that you're using `hdparm -u 1' against the
> relevant disk?
>
> - The serial port is working OK, but the application which is handling
> serial IO is blocked on a disk read (something got paged out), and
> that disk read fails to complete by the time the serial port buffer
> fills up.
>
> I'll send you a patch which makes the VM less inclined to page things
> out in the presence of heavy writes, and which decreases read
> latencies.
>
Is this patch posted anywhere?
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