Re: Linux-2.2.0 bad VM behaviour "dd if=/dev/zero of=/dev/hdc bs=256k"
Andi Kleen (ak@muc.de)
Thu, 28 Jan 1999 19:13:50 +0100
On Thu, Jan 28, 1999 at 08:24:18AM +0100, Petri Mattila wrote:
> At 11:17 AM 1/27/99 -0800, Linus Torvalds wrote:
>
> >This is one of my peeves - we should really start the IO once we've filled
> >up "X nr" of full buffers. But I've always been too lazy to do it.
>
> But could somebody please explain why on earth processes get swapped out
> if I turn on DMA transfer, but stay in memory with PIO transfer?
One possible explanation could be that PIO mode is much slower and eats more
CPU time, so the kswapd has more(less(?)) time to swap things out.
This is only a crazy theory @)
-Andi
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