Messages in this thread | | | Date | Fri, 12 Sep 2003 12:51:52 -0700 | Subject | Re: Memory mapped IO vs Port IO | From | (Jesse Barnes) |
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On Fri, Sep 12, 2003 at 11:58:07AM -0700, Martin J. Bligh wrote: > >> Also - a perhaps more useful test is a write followed by a read. > > > > Well, someone else will have to run that test. On Altix, a read() is > > freakishly expensive, and I'm not really interested in showing everyone > > how bad it is ;) > > I find percentile comparisons useful for hiding the embarassement > of occasional hardware realities ;-) (ie what's the speed *ratio* > between the two types of read).
Well, in our case, read() and in() will be pretty close, percentage-wise. The read() in itself is so bad that I think the additional badness of in() will be mostly hidden.
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