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.
Thanks.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:28 EST