Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation

Thomas Graf
2015-12-09T02:42:53Z

On 12/09/15 at 10:38am, Herbert Xu wrote:
> On Wed, Dec 09, 2015 at 03:36:32AM +0100, Thomas Graf wrote:
> >
> > Without knowing your exact implementation plans: introducing an
> > additional reference indirection for every lookup will have a
> > huge performance penalty as well.
> >
> > Is your plan to only introduce the master table after an
> > allocation has failed?
>
> Right, obviously the extra indirections would only come into play
> after a failed allocation. As soon as we can run the worker thread
> it'll try to remove the extra indirections by doing vmalloc.

OK, this sounds like a good compromise. The penalty is isolated
for the duration of the atomic burst.