Re: [PATCH] likely cleanup: revert unlikely in ll_back_merge_fn

[Jens Axboe <axboe@suse.de>]

On Tue, Apr 25 2006, Hua Zhong wrote:
> With likely/unlikely profiling (see the recent patch dwalker@mvista.com 
> sent), on my not-so-busy-typical-development system it shows more than 
> 80K misses and no hits. So I guess it makes sense to revert.
> 
> I don't know BIO code very well, but I hope this data is useful for the 
> experts.

Well you'd want to optimize for the busy case, right, no point in
optimizing for a more idle system.

I'm not at all uninterested in this, I'd just like to see a more
intelligent/controlled work load that actually stresses the io subsystem
being profiled. If you have a not-so-busy system, you like don't do
enough IO to trigger a lot of merges. Or maybe you do, and we just have
a bug somewhere so that we unfortunately repeatedly recount segments.

Care to run a simple io benchmark and profile that?

-- 
Jens Axboe