Re: Locking comment on shrink_caches()

[Marcelo Tosatti]

On Tue, 25 Sep 2001, David S. Miller wrote:

>    From: Marcelo Tosatti <[e-mail]>
>    Date: Tue, 25 Sep 2001 15:40:23 -0300 (BRT)
>    
>    We can simply lock the pagecachelock and the pagemap_lru_lock at the
>    beginning of the cleaning function. page_launder() use to do that.
>    
>    Thats why I asked Andrea if there was long hold times by shrink_caches().
>    
> Ok, I see.
> 
> I do think it's silly to hold the pagecache_lock during pure scanning
> activities of shrink_caches().

It may well be, but I would like to see some lockmeter results which show
that _shrink_cache()_ itself is a problem. :)

> It is known that pagecache_lock is the biggest scalability issue on
> large SMP systems, and thus the page cache locking patches Ingo and
> myself did.

Btw, is that one going into 2.5 for sure? (the per-address-space lock).