From: Jakub Kicinski <kuba@kernel.org>
To: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: Michael Chan <michael.chan@broadcom.com>,
davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
pabeni@redhat.com, gospo@broadcom.com, bpf@vger.kernel.org,
somnath.kotur@broadcom.com,
Ilias Apalodimas <ilias.apalodimas@linaro.org>
Subject: Re: [PATCH net-next 3/3] bnxt_en: Let the page pool manage the DMA mapping
Date: Mon, 31 Jul 2023 11:00:08 -0700 [thread overview]
Message-ID: <20230731110008.26e8ce03@kernel.org> (raw)
In-Reply-To: <2eadb48b-2991-7458-16a6-51082ff3ec2c@kernel.org>
On Mon, 31 Jul 2023 19:47:08 +0200 Jesper Dangaard Brouer wrote:
> > This should be smaller than PAGE_SIZE only if you're wasting the rest
> > of the buffer, e.g. MTU is 3k so you know last 1k will never get used.
> > PAGE_SIZE is always a multiple of BNXT_RX_PAGE so you waste nothing.
>
> Remember pp.max_len is used for dma_sync_for_device.
> If driver is smart, it can set pp.max_len according to MTU, as the (DMA
> sync for) device knows hardware will not go beyond this.
> On Intel "dma_sync_for_device" is a no-op, so most drivers done
> optimized for this. I remember is had HUGE effects on ARM EspressoBin board.
Note that (AFAIU) there is no MTU here, these are pages for LRO/GRO,
they will be filled with TCP payload start to end. page_pool_put_page()
does nothing for non-last frag, so we'll only sync for the last
(BNXT_RX_PAGE-sized) frag released, and we need to sync the entire
host page.
next prev parent reply other threads:[~2023-07-31 18:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-28 23:18 [PATCH net-next 0/3] bnxt_en: Add support for page pool Michael Chan
2023-07-28 23:18 ` [PATCH net-next 1/3] bnxt_en: Fix page pool logic for page size >= 64K Michael Chan
2023-07-29 0:35 ` Jakub Kicinski
2023-07-28 23:18 ` [PATCH net-next 2/3] bnxt_en: Use the unified RX page pool buffers for XDP and non-XDP Michael Chan
2023-07-28 23:18 ` [PATCH net-next 3/3] bnxt_en: Let the page pool manage the DMA mapping Michael Chan
2023-07-29 0:42 ` Jakub Kicinski
2023-07-31 17:47 ` Jesper Dangaard Brouer
2023-07-31 18:00 ` Jakub Kicinski [this message]
2023-07-31 18:16 ` Michael Chan
2023-07-31 18:44 ` Jakub Kicinski
2023-07-31 20:20 ` Michael Chan
2023-07-31 20:44 ` Jakub Kicinski
2023-07-31 21:11 ` Michael Chan
2023-08-01 17:06 ` Jesper Dangaard Brouer
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