Re: [PATCH 10/11] io_uring/rsrc: cache struct io_rsrc_node

[Pavel Begunkov]

On 3/31/23 15:09, Gabriel Krisman Bertazi wrote:
> Pavel Begunkov <asml.silence@xxxxxxxxx> writes:
>
> > Add allocation cache for struct io_rsrc_node, it's always allocated and
> > put under ->uring_lock, so it doesn't need any extra synchronisation
> > around caches.
>
> Hi Pavel,
>
> I'm curious if you considered using kmem_cache instead of the custom
> cache for this case?  I'm wondering if this provokes visible difference in
> performance in your benchmark.

I didn't try it, but kmem_cache vs kmalloc, IIRC, doesn't bring us
much, definitely doesn't spare from locking, and the overhead
definitely wasn't satisfactory for requests before.

A quick note that I want to further limit the cache size,
IO_ALLOC_CACHE_MAX=512 for nodes doesn't sound great.

--
Pavel Begunkov