SJS wrote:
A specialized controller will always outperform a general-purpose processor, all other things being equal.
Sure it will. But the bang/buck isn't as great. And today's general purpose processors usually have tons of spare processing power. The IO usually isn't fast enough to keep them busy. So rather than invest in a dedicated processor we get more use out of the general purpose process the machine comes with.
So the only performance-related distinctions that have any meaning are the architectural ones. Everything else will average out. As for economics, well, if you are requiring your main processor to do more work, you need to invest in a faster processor. Which gets more
Not if the main processor is as underutilized as it typically is.
I believe it was Tracy that mentioned using the MMX capabilities to compute checksums. That's where I think we'll see more happen -- with filesystems like ZFS pushing integrity issues closer to the general purpose processor, and then general-purpose processors incorporating custom hardware to pull that computation out of software and into the hardware, where it can be fast.
Yes, it was me. Linux has used MMX for RAID5 XOR'ing for years. Pretty much since MMX came along since it was an obvious and relatively easy thing to implement.
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