Re: kernel memory allocators

[Allen Briggs <briggs%netbsd.org@localhost>]

On Wed, Jan 19, 2011 at 05:55:57PM +0100, Lars Heidieker wrote:
> > What are the benefits that you expect to see from doing this work?
> > Have you measured to see if those benefits are realized?
> 
> Benefits I've thought about:
> - The kmem pools use pool_caches therefor scalability will be much
> better as the old malloc has a single lock for all access, the pools
> have one each with a per cpu cache layer.
> - The old malloc only returns oversized allocations back to the kmem
> layer but nothing that is in it's bucket, pools can be drained...
> - Removing one redundant interface in the kernel-api (in the long
> term, when dropping the malloc wrapper)

Fair enough.  Do you have any measurements to see if the benefits are
realized?  Does it actually (not just theoretically) scale better?
Does draining happen and the system behave better in low-memory
situations?  Does it stay up when it would panic/crash/stall before?
What is the code size savings for getting rid of the malloc code (and
leaving a shim or not)?

> I am in the progress of some cleanup work, I'll make a patch available
> within the next few days.

Cool!

-allen

-- 
Allen Briggs  -  briggs%ninthwonder.com@localhost