netdev - Re: [PATCH net-next v4 4/6] enic: Use the Page Pool API for RX when MTU is less than page size

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Message-ID: <20250104174152.67e3f687@kernel.org>
Date: Sat, 4 Jan 2025 17:41:52 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: John Daley <johndale@...co.com>
Cc: benve@...co.com, satishkh@...co.com, andrew+netdev@...n.ch,
 davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
 netdev@...r.kernel.org, Nelson Escobar <neescoba@...co.com>
Subject: Re: [PATCH net-next v4 4/6] enic: Use the Page Pool API for RX when
 MTU is less than page size

On Thu,  2 Jan 2025 14:24:25 -0800 John Daley wrote:
> The Page Pool API improves bandwidth and CPU overhead by recycling
> pages instead of allocating new buffers in the driver. Make use of
> page pool fragment allocation for smaller MTUs so that multiple
> packets can share a page.

Why the MTU limitation? You can set page_pool_params.order 
to appropriate value always use the page pool.

> Added 'pp_alloc_error' per RQ ethtool statistic to count
> page_pool_dev_alloc() failures.

SG, but please don't report it via ethtool. Add it in 
enic_get_queue_stats_rx() as alloc_fail (and enic_get_base_stats()).
As one of the benefits you'll be able to use
tools/testing/selftests/drivers/net/hw/pp_alloc_fail.py
to test this stat and error handling in the driver.

> +void enic_rq_page_cleanup(struct enic_rq *rq)
> +{
> +	struct vnic_rq *vrq = &rq->vrq;
> +	struct enic *enic = vnic_dev_priv(vrq->vdev);
> +	struct napi_struct *napi = &enic->napi[vrq->index];
> +
> +	napi_free_frags(napi);

why?

> +	page_pool_destroy(rq->pool);
> +}
-- 
pw-bot: cr