On Monday 02 March 2009 09:11:54 Linus Torvalds wrote: > The thing is, with PIO, a 512-byte disk read ends up doing 256 16-bit word > reads from the controller, each potentially up to 600ns long (PIO0 > timings). That's 150ms - for a single sector! Out of curiosity, the peanut gallery wishes to ask: Is the above supposed to be 600us (*1000), or 150us (/1000)? Probably the latter. > For example, Mode2 timings are probably still something we should consider > realistic, and that's 240ns per word - a single sector now takes ~60ms to > read off the disk. Same factor of 1000 question here. > And we don't do single sectors. Most transfers will be 8 sectors (4k > contiguos read). So now that 60ms is 480ms per such IDE interrupt. And > even with the _good_ timings, we're certainly looking at a reduction of > that to about half. > > Imagine what happens when we have interrupts disabled for half a second at > a time. -- Vadim Lobanov -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
