On Thu, 2007-11-01 at 15:29 +0100, Nick Piggin wrote:
> On Thu, Nov 01, 2007 at 03:06:05PM +0100, Peter Zijlstra wrote:
> > On Thu, 2007-11-01 at 15:02 +0100, Nick Piggin wrote:
> >
> > > Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
> > > decouple it from the spinlock implementation, and make it typesafe (rwlocks
> > > do not have any need_lockbreak sites -- why do they even get bloated up
> > > with that break_lock then?).
> >
> > IIRC Lee has a few patches floating about that do introduce lockbreak
> > stuff for rwlocks.
>
> Well that would be a good reason to introduce a break_lock for them,
> but previously not so much... we have rwlocks in some slightly space
> critical structures (vmas, inodes, etc).
>
> I guess it was done to make the "template" hacks eaiser. I don't really
> find that in good taste, especially for important core infrastructure.
> Anyway.
Actually, what I had/have is a cond_resched_rwlock() that I needed to
convert the i_mmap_lock() to rw for testing reclaim scalability. [I've
seen a large system running an Oracle OLTP load hang spitting "cpu soft
lockup" messages with all cpus spinning on a i_mmap_lock spin lock.]
One of the i_mmap_lock paths uses cond_resched_lock() for spin locks.
To do a straight forward conversion [and maybe that isn't the right
approach], I created the cond_resched_rwlock() function by generalizing
the cond_sched_lock() code and creating both spin and rw lock wrappers.
I took advantage of the fact that, currently, need_lockbreak() is a
macro and that both spin and rw locks have/had the break_lock member.
Typesafe functions would probably be preferrable, if we want to keep
break_lock for rw spin locks.
Here's the most recent posting:
http://marc.info/?l=linux-mm&m=118980356306014&w=4
See the changes to sched.[ch]. Should apply to 23-mm1 with offsets and
minor fixup in fs/inode.c.
Lee
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
