[illumos-Developer] Changing sd_io_time to 8?

[Mike La Spina]

>From the risk flags put up on the sd_io_time modification, would it be
prudent to just use the dreaded sd.conf tunable? Yes I know, not another
one of those arcane tuning parms that nobody can recall and set without
reading source. However sd does have a man page to hold this info .....
it's not a great solution but when correctly targeted it does prevent
some ugly slow hardware recovery scenarios with JBODs that many people
curse at. (myself included)


-----Original Message-----
From: Garrett D'Amore [mailto:garrett at nexenta.com] 
Sent: Tuesday, May 03, 2011 11:48 AM
To: Dan McDonald
Cc: developer at lists.illumos.org
Subject: Re: [illumos-Developer] Changing sd_io_time to 8?

On Tue, 2011-05-03 at 12:32 -0400, Dan McDonald wrote:
> On Tue, May 03, 2011 at 05:22:32PM +0100, Deano wrote:
> 
> <SNIP!>
> 
> > It is exactly this kind of confusion, which is why I believe why SD
is
> > overburdened, also from the source code which at IIRC 13K+ LOC is
well
> > above most software engineering thoughts on file size indicates it
to me.
> 
> Well SOMETHING had to take the place of ip.c as biggest source file in
the
> kernel.  ;)

Oh, I can probably think of several bigger files, and certainly bigger
*drivers*.

None of which means this is a good example to follow.  There is no
reason that sd should be more than about 5 or 6KLOC -- except that it is
filled with logic for too many different types of devices, and to deal
with too many exceptions.

I've contemplated a major overhaul of this driver in the past.

If nothing else, the tunable mechanism is so arcanely byzantine, that
nobody can reasonably use it without spending time reading the code --
yet there are a significant number of things in that driver that you
really *do* want to tune for different types of devices.

	- Garrett
> 
> Dan
> 
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