From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Alejandro Lucero <alejandro.lucero@netronome.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] nfp: handle packets with length 0 as usual ones
Date: Tue, 22 Aug 2017 17:16:03 +0100 [thread overview]
Message-ID: <8384d299-ecb0-de14-4c01-75d8e9b0af7b@intel.com> (raw)
In-Reply-To: <1503398486-1944-1-git-send-email-alejandro.lucero@netronome.com>
On 8/22/2017 11:41 AM, Alejandro Lucero wrote:
> A DPDK app could, whatever the reason, send packets with size 0.
> The PMD is not sending those packets, which does make sense,
> but the problem is the mbuf is not released either. That leads
> to mbufs not being available, because the app trusts the
> PMD will do it.
>
> Although this is a problem related to app wrong behaviour, we
> should harden the PMD in this regard. Not sending a packet with
> size 0 could be problematic, needing special handling inside the
> PMD xmit function. It could be a burst of those packets, which can
> be easily handled, but it could also be a single packet in a burst,
> what is harder to handle.
>
> It would be simpler to just send that kind of packets, which will
> likely be dropped by the hw at some point. The main problem is how
> the fw/hw handles the DMA, because a dma read to a hypothetical 0x0
> address could trigger an IOMMU error. It turns out, it is safe to
> send a descriptor with packet size 0 to the hardware: the DMA never
> happens, from the PCIe point of view.
>
> Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
Applied to dpdk-next-net/master, thanks.
prev parent reply other threads:[~2017-08-22 16:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-22 10:41 Alejandro Lucero
2017-08-22 16:16 ` Ferruh Yigit [this message]
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