On Mon, Sep 11 2006, Alan Cox wrote: > Ar Llu, 2006-09-11 am 10:44 -0400, ysgrifennodd Jeff Garzik: > > > drivers/ide. You might want to do 256 for SATA Jeff but please don't do > > > 256 for PATA. Reading specs is too hard for some people ;) > > > > > > Some drives abort the xfer, some just choked. > > > > Where in drivers/ide is it limited to 255? > > Being a sensible sanity check it was removed, and that was a small > mistake. Some 2.4 also has a 256 limit and it broken various transparent > raid units, older Maxtors(1Gb or so), some IBM drives etc. Got fixed in > -ac but never in base. > > The failure pattern is pretty ugly too, your box runs and runs and > eventually you get a linear 256 sector I/O and it all blows up, > sometimes. The IBM's abort the xfer but the maxtors may or may not get > it right (its as if half the firmware has the right test). So this is a confirmed, broken case? Why has no one complained for 2.4 and 2.6? > We could perhaps do it by ATA version - 255 for ATA < 3 256 for ATA 3+, Might be sane, yep. > lots for LBA48 ? Thats assuming you can show 256 sectors is faster than > 255. I'd bet for normal I/O its unmeasurably small. 255 isn't faster than 256, measurably. But the alignment for "natural" transfer sizes is much nicer with 256, that's the problem. You really don't want 248 + 8 going down all the time, for instance. Perhaps it's not a real problem, but it could be. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
