On Mon, 12 Jan 2004 Conor_D_Wynne at Dell.com wrote:
> AFAIK You're fine until you go above 16GB [or hit 16GB that is]
Nope. First slowdown is once you install more than 1GB in an i386.
After that, kernel can no longer be mapped into each processes
address space and you take a vm context swap on each transition
between kernel and process vm context (interrupts/system calls).
The next slow down is > 4GB, then you're using PAE which introduces
an additional level of indirection in page tables. And IO to/from
data located above 4GB physical has to be bounce buffered.
Now, 2.4 appears to have a CONFIG_HIGHIO which says:
"If you want to be able to do I/O to high memory pages, say Y.
Otherwise low memory pages are used as bounce buffers causing a
degrade in performance."
But I see little reference to it, and I cant think how it would work
on i386. anyone know?
Paul Jakma paul at clubi.iepaul at jakma.org Key ID: 64A2FF6A
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