Re: IDE-DMA strangeness (another one)

Mark Lord (
Fri, 04 Dec 1998 15:23:48 +0000

John Kodis wrote:

> I get a similar speed, but don't understand why. I would expect that
> given a 4-byte wide bus clocked at 33MHz performing a read from cache
> and a write into the destination userspace buffer, the buffer cache
> read speed should be more like 66MB/s. Is there another read/write
> pair that I've overlooked?

Just the CPU and memory speeds. Small details. :)

Here is a P2-400 with SDRAM:

Timing buffer-cache reads: 128 MB in 1.20 seconds =106.67 MB/sec

Sometimes it measures faster, like 124 MB/sec, depending on kernel


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