Dear Bret,

> The article is found at

> I mostly agree with you and your article, but:

fine that you agree,  but at most 50% of the article is even close to

>>> Conclusion
>>> CPU-bound benchmarks are much faster on a modern machine than they
>>> are on older ones.
>>> The frequency increase does not actually suffice to explain the
>>> speedup.
>>> Some things, like doing I/O, were not sped up nearly as much
>>> however.

> I tried posting a much longer response to this, but it was
> apparently rejected by the moderators.  Here's a shorter one.

>> I/O has also vastly speedup (we have SSD speeds of up to 6 GB/sec).
>> Just not by doing IN/OUT, but by using memory mapped PCI devices.

> I think you're confusing two different things -- MMIO and DMA/Bus-Mastering.

He is NOT.

> Whether I/O is PMIO or MMIO is pretty much irrelevant to the speed.
> For example, I/O port 201h (the analog joystick) and I/O port 92h
> (which controls A20 on some computers) are both VERY slow and would
> not be any faster if they were MMIO instead of PMIO.

this is plain bullshit.

> The speed depends on the I/O device, not the type of I/O mapping.
which is nonsense.

>  Plus, I/O
> _can't_ be cached, whether PMIO or MMIO, so the cache(s) are irrelevant to 
> I/O.

yes. I/O device data can't be cached. you are such a clever person to
discover this fact. WOW.

> SSD speeds are fast because they use bus-mastering, not because
> they use MMIO.  The I/O ports are used to "control" the device, but
> the data from the SSD is transferred in and out of RAM using
> bus-mastering (which is fast because it doesn't use the CPU at all).

I understand that you don't have the faintest clue how modern PCI devices
work. Just go ahead with undertaining us ...


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