twa is giant locked in 7-Current or everywhere?

Kris Kennaway kris at
Wed Aug 15 10:42:19 PDT 2007

On Wed, Aug 15, 2007 at 09:09:33PM +0400, Artem Kuchin wrote:
> Hi!
> When i installed twas driver on 6.2-STABLE it said
> [FAST]
> i presumed that it measn that twa is giant-lock free.
> Now, after installing 7-CURRENT i see
> Aug 15 17:00:02 omni3 kernel: 3ware device driver for 9000 series storage 
> controllers, version:
> Aug 15 17:00:02 omni3 kernel: twa0: <3ware 9000 series Storage Controller> 
> port 0x3000-0x30ff mem 0x88000000-0x89ffffff,0x8a200000-0x8a200fff irq 16 
> at devic
> Aug 15 17:00:02 omni3 kernel: twa0: [GIANT-LOCKED]
> Aug 15 17:00:02 omni3 kernel: twa0: [ITHREAD]
> So, it says GIANT-LOCKED and then ITHREAD.
> Apparently, i have no real understaning what those words mean.
> COuld anyone explain the meaning of
> Giant-locked is self explanatory and.. bad.

I think 6.x doesn't display the GIANT-LOCKED messages because users
were freaking out too much after they were added at an earlier point
in 6.x development ("Q: why is this driver suddenly giant locked?" "A:
It's always been giant locked, now this fact is displayed as a note to

While it's true that a non-giant locked driver would be better, it's
not as bad as you might think because almost nothing else requires
giant for most workloads thesedays (see, so in those workloads performance
will not be worse because of it.  If you are really bothered by this
you can enable mutex profiling to check how much of a problem it is
for you.

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