netdev - Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for custom page providers

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Date: Mon, 3 Jun 2024 07:17:05 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Christoph Hellwig <hch@...radead.org>
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Subject: Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for
 custom page providers

On Fri, May 31, 2024 at 10:35 PM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Thu, May 30, 2024 at 08:16:01PM +0000, Mina Almasry wrote:
> > I'm unsure if the discussion has been resolved yet. Sending the series
> > anyway to get reviews/feedback on the (unrelated) rest of the series.
>
> As far as I'm concerned it is not.  I've not seen any convincing
> argument for more than page/folio allocator including larger order /
> huge page and dmabuf.
>

Thanks Christoph, this particular patch series adds dmabuf, so I
assume no objection there. I assume the objection is that you want the
generic, extensible hooks removed.

To be honest, I don't think the hooks are an integral part of the
design, and at this point I think we've argued for them enough. I
think we can easily achieve the same thing with just raw if statements
in a couple of places. We can always add the hooks if and only if we
actually justify many memory providers.

Any objections to me removing the hooks and directing to memory
allocations via simple if statements? Something like (very rough
draft, doesn't compile):

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 92be1aaf18ccc..2cc986455bce6 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -557,8 +557,8 @@ netmem_ref page_pool_alloc_netmem(struct page_pool
*pool, gfp_t gfp)
                return netmem;

        /* Slow-path: cache empty, do real allocation */
-       if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_ops)
-               netmem = pool->mp_ops->alloc_pages(pool, gfp);
+       if (unlikely(page_pool_is_dmabuf(pool)))
+               netmem = mp_dmabuf_devmem_alloc_pages():
        else
                netmem = __page_pool_alloc_pages_slow(pool, gfp);
        return netmem;


-- 
Thanks,
Mina