Re: [PATCH V5,net-next] net: mana: Add page pool for RX buffers

From: Jesper Dangaard Brouer
Date: Fri Aug 04 2023 - 06:52:53 EST

On 03/08/2023 03.44, Jesse Brandeburg wrote:
On 8/2/2023 11:07 AM, Haiyang Zhang wrote:
Add page pool for RX buffers for faster buffer cycle and reduce CPU

Can you add some info on the performance improvement this patch gives?

Your previous post mentioned:
> With iperf and 128 threads test, this patch improved the throughput by 12-15%, and decreased the IRQ associated CPU's usage from 99-100% to 10-50%.

The standard page pool API is used.

Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
In err path, set page_pool_put_full_page(..., false) as suggested by
Jakub Kicinski
Add nid setting, remove page_pool_nid_changed(), as suggested by
Jesper Dangaard Brouer
Update xdp mem model, pool param, alloc as suggested by Jakub Kicinski
Use the standard page pool API as suggested by Jesper Dangaard Brouer

diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index 024ad8ddb27e..b12859511839 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -280,6 +280,7 @@ struct mana_recv_buf_oob {
struct gdma_wqe_request wqe_req;
void *buf_va;
+ bool from_pool; /* allocated from a page pool */

suggest you use flags and not bools, as bools waste 7 bits each, plus
your packing of this struct will be full of holes, made worse by this
patch. (see pahole tool)


/* SGL of the buffer going to be sent has part of the work request. */
u32 num_sge;
@@ -330,6 +331,8 @@ struct mana_rxq {
bool xdp_flush;
int xdp_rc; /* XDP redirect return code */
+ struct page_pool *page_pool;
* Each receive buffer has an associated mana_recv_buf_oob.

The rest of the patch looks ok and is remarkably compact for a
conversion to page pool. I'd prefer someone with more page pool exposure
review this for correctness, but FWIW

Both Jakub and I have reviewed the page_pool parts, and I think we are
in a good place.

Looking at the driver, I wonder why you are keeping the driver local
memory cache (when PP is also contains a memory cache) ?
(I assume there is a good reason, so this is not blocking patch)

Reviewed-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>

Thanks for taking your time to review.

I'm ready to ACK once the description is improved a bit :-)

pw-bot: cr