Re: [RFC] I/O Access Abstractions

From: Alan Cox (
Date: Thu Jun 28 2001 - 08:32:42 EST

> Also on an i386, the actual I/O instruction itself is going to take a
> comparatively long time anyway, given the speed differential between CPU
> and external buses.

PCI memory (and sometimes I/O) writes are posted, Since x86 memory writes are
also parallelisable instructions and since the CPU merely has to retire the
writes in order your stall basically doesnt exist.

High end devices tend to have you writing them to them and they DMA into your
RAM so its a concern

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This archive was generated by hypermail 2b29 : Sat Jun 30 2001 - 21:00:18 EST