Re: [PATCH] block: strip out locking optimization in put_io_context()

[Linus Torvalds]

On Wed, Feb 8, 2012 at 8:29 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
>
> Can you please try the following one?  Thanks a lot!

If you can use it as a rwlock, why can't you do it with RCU?

Usually rwlocks are a bad idea. They tend to be more expensive than
spinlocks, and the extra parallelism is almost never noticeable
(except as "more cacheline bounces") for something that is appropriate
for a non-sleeping lock.

There's a *very* few situations where rwlock is the right thing, but
it really almost always is a horribly bad idea.

                     Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/