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bio website jb.org
location Denver, CO
age 40
visits member for 3 years, 8 months
seen Aug 16 '13 at 19:58
The best thing for being sad,” replied Merlin, beginning to puff and blow, “is to learn something. That’s the only thing that never fails. You may grow old and trembling in your anatomies, you may lie awake at night listening to the disorder of your veins, you may miss your only love, you may see the world about you devastated by evil lunatics, or know your honour trampled in the sewers of baser minds. There is only one thing for it then — to learn. Learn why the world wags and what wags it. That is the only thing which the mind can never exhaust, never alienate, never be tortured by, never fear or distrust, and never dream of regretting. Learning is the only thing for you. Look what a lot of things there are to learn.
—T.H. White, The Once and Future King

Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
The high end HBA's do not require the host CPU to decode command packets, or reorder them for example. The CPU on the HBA does this. The work is "off loaded" to the HBA. Also, they do not need to block the host CPU for storage space as the bytes come in off the bus, only when they need to push a completed block into main RAM - "off-loading" the need to hold system RAM blocked with the CPU in iowait.
Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
This is part of why I'd like to see the full off-load. For example, a chip without any place to store data as it comes in may say "Hold on CPU (go into IO-wait)", then dribble the bytes as they come in off the wire into RAM, then let the CPU have RAM access back again. A disk drive controller card with its own CPU/RAM would only interrupt the CPU (appearing as "cpu usage") to copy the data from its RAM down the PCI BUS to system RAM.
Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
(And more to the point, are there any that only do the DMA transfer after taking a full block / unit of data off the bus)
Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
@ChrisS Yes, this is true. Do you even know of a 1394 card that offloads transfers the way the HDD cards do?
Feb
28
revised Does any USB controller card exist that fully offloads I/O from the host CPU?
Clarified question, as 3 folks have answered on different topics so far (DMA / 1394)
Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
@IgnacioVazquez-Abrams - I know your response was a joke. But there's apparently not even any 1394 cards that fully offload transfers the way the SAS / high-end SATA cards do.
Feb
28
awarded  Student
Feb
28
awarded  Editor
Feb
28
comment Does any USB controller card exist that fully offloads I/O from the host CPU?
Thanks! Do you know of any? Is there a single example? :-)
Feb
28
revised Does any USB controller card exist that fully offloads I/O from the host CPU?
Corrected grammar. Oops. :-(
Feb
28
asked Does any USB controller card exist that fully offloads I/O from the host CPU?
Dec
21
awarded  Autobiographer