lkml.org 
[lkml]   [2006]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: What's in libata-dev.git
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-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-09-11 17:41    [W:0.439 / U:1.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site