Re: Warning - running *really* short on DMA buffers while doingfile transfers

Andrew Morton
2002-09-27T19:02:37Z

"Justin T. Gibbs" wrote:
>
> ...
> > The evidence is here:
> >
> > http://marc.theaimsgroup.com/?l=linux-kernel&m=103302456113997&w=1
>
> Which unfortunately characterizes only a single symptom without breaking
> it down on a transaction by transaction basis. We need to understand
> how many writes were queued by the OS to the drive between each read to
> know if the drive is actually allowing writes to pass reads or not.
>

Given that I measured a two-second read latency with four tags,
that would be about 60 megabytes of write traffic after the
read was submitted. Say, 120 requests. That's with a tag
depth of four.

Not sure how old the disk is. It's a 36G Fujitsu SCA-2. Manufactured
in 2000, perhaps??