On Tue, 2009-04-14 at 19:39 -0600, Robert Hancock wrote: > James Bottomley wrote: > > > > On a final note about the urgency of getting libata out of SCSI: Intel > > has been worrying for a while about the fatness of the SCSI/libata > > stack, and its effects on performance, especially command transmission > > via SAT, so I'm hoping they'll be supporting the effort. > > I really don't see this as being a big driver for this move. If you look > at the code that does the translation of SCSI commands to ATA commands, > there really is not much there at all of any consequence to CPU usage. > Compared to any kind of hardware/controller interactions I wouldn't say > it's likely to be a significant bottleneck at all. In oprofile runs I've > done with heavy ATA activity, the top time consumers are the interrupt > handlers, command issue paths, code that actually is poking IO > registers. The libata-scsi code hasn't even shown up on the radar in my > experience. Been there, said that and got the nicely embroidered polo shirt to prove it. The point is, it doesn't really matter what I say or believe, it matters what they do ... and they believe fat stacks impede the performance of their SSDs. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
