[Unionfs] INgo Molnar's RT patch

[Josef Sipek]

On Tue, Aug 21, 2007 at 02:27:41PM +0200, Paul Hewlett wrote:
> Hi Erez
> 
> I like to live dangerously so I am experimenting with Ingo Molnar's RT patch 
> for linux. 
> 
> I am using Gentoo kernel 2.6.21-gentoo-r4. I applied linux-2.6.21.5-u1.diff.gz 
> patch for unionfs - this applied cleanly with some minor mods to the 
> Makefile. I then applied the patch-2.6.21.6-rt21 from Ingo Molnar's site - I 
> had to do some hand-hacking. 
> 
> When I compiled, the file fs/unionfs/inode.c failed. A 
> structure 'rw_semaphore' was being used and this did not now exist. I 
> discovered that if I changed the declaration of rwsem in union.h at line 146 
> in the declaration of struct unionfs_sb_info from
> 
>       struct rw_semaphore rwsem;
> 
> to 
> 
>       struct compat_rw_semaphore rwsem;
> 
> then everything compiled.
> 
> Hope this info is helpful. Is there any test scenario with this that you would 
> like me to try ?
 
Ingo's patch series basically rewrites the locking in the entire kernel. I
can't think of anything specific to test, if the compat_rw_semaphore acts
the same way rw_semaphore does in Linus's tree, things should just work.

Hrm...I can't even have you run the regression suite because the latest
revision is not publicly available...oh, well, the never ending todo list
expands once again :)

> The kernel boots quite happily and I have also enabled the nvidia drivers - 
> in fact I am sending this email from the PC in question.

Good to hear.

Jeff.

-- 
A CRAY is the only computer that runs an endless loop in just 4 hours...