Messages in this thread | | | Date | Tue, 16 May 2006 13:27:08 -0400 | From | Jeff Garzik <> | Subject | Re: PATCH: Fix broken PIO with libata |
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Kevin Radloff wrote: > On 5/16/06, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: >> On Maw, 2006-05-16 at 11:33 -0400, Kevin Radloff wrote: >> > However, I still have a problem with pata_pcmcia (that I actually >> > experienced also with the ide-cs driver) where sustained reading or >> > writing to the CF card spikes the CPU with nearly 100% system time. >> >> That is normal. The PCMCIA devices don't support DMA. As a result of >> this the processor has to fetch each byte itself over the ISA speed >> PCMCIA bus link. > > Hrm, as I recall that only started happening with ide-cs sometime in > the single digits of 2.6.x.. And note that it's only maxing out at > about 1.5MB/s. Should that saturate my laptop's 1.1GHz Pentium M > processor?
Doing data xfer using PIO rather than DMA definitely eats tons of CPU cycles.
Jeff
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