Re: [PATCH] allow vma merging with mlock et. al.

[Chris Wright]

* Darren Hart (dvhltc@xxxxxxxxxx) wrote:
> As I understand it, the reason we don't merge is because 
> it is expected that a task will lock and unlock the same memory range 
> more than once and we don't want to waste our time merging and splitting 
> the VMAs.

I don't have a good sampling of applications.  The one's I've used are
temporal like gpg, or they mlockall the whole thing and never look back.
But I did a quick benchmark since I was curious, a simple loop of a
million lock/unlock cycles of a page that could trigger a merge:

vanilla
(no merge): 659706 usecs

patched
(merge):    3567020 usecs

Heh, I was surprised to see it that much slower.

cheers,
-chris
-- 
Linux Security Modules     http://lsm.immunix.org     http://lsm.bkbits.net
-
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/