On Fri, May 01, 2009 at 08:31:12AM +0200, Andi Kleen wrote:
> Frederic Weisbecker <fweisbec@xxxxxxxxx> writes:
> >
> > diff --git a/include/linux/reiserfs_fs.h b/include/linux/reiserfs_fs.h
> > index 6587b4e..397d281 100644
> > --- a/include/linux/reiserfs_fs.h
> > +++ b/include/linux/reiserfs_fs.h
> > @@ -1302,7 +1302,13 @@ static inline loff_t max_reiserfs_offset(struct inode *inode)
> > #define get_generation(s) atomic_read (&fs_generation(s))
> > #define FILESYSTEM_CHANGED_TB(tb) (get_generation((tb)->tb_sb) != (tb)->fs_gen)
> > #define __fs_changed(gen,s) (gen != get_generation (s))
> > -#define fs_changed(gen,s) ({cond_resched(); __fs_changed(gen, s);})
> > +#define fs_changed(gen,s) \
> > +({ \
> > + reiserfs_write_unlock(s); \
> > + cond_resched(); \
> > + reiserfs_write_lock(s); \
>
> Did you try writing that
>
> if (need_resched()) { \
> reiserfs_write_unlock(s); \
> cond_resched(); \ (or schedule(), but cond_resched does a loop)
> reiserfs_write_lock(s); \
> }
>
> ? That might give better performance under load because users will be better
> batched and you don't release the lock unnecessarily in the unloaded case.
Good catch!
And I guess this pattern matches most of the cond_resched()
all over the code (the only condition is that we must already hold
the write lock).
I will merge your idea and Ingo's one, write a
reiserfs_cond_resched() to have a helper which
factorizes this pattern.
Thanks.
> -Andi
>
> --
> ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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