[dpdk-dev] [PATCH v1] ixgbe_pmd: forbid tx_rs_thresh above 1 for all NICs but 82598
didier.pallard
didier.pallard at 6wind.com
Fri Sep 11 16:25:12 CEST 2015
On 08/25/2015 08:52 PM, Vlad Zolotarov wrote:
>
> Helin, the issue has been seen on x540 devices. Pls., see a chapter
> 7.2.1.1 of x540 devices spec:
>
> A packet (or multiple packets in transmit segmentation) can span any
> number of
> buffers (and their descriptors) up to a limit of 40 minus WTHRESH
> minus 2 (see
> Section 7.2.3.3 for Tx Ring details and section Section 7.2.3.5.1 for
> WTHRESH
> details). For best performance it is recommended to minimize the
> number of buffers
> as possible.
>
> Could u, pls., clarify why do u think that the maximum number of data
> buffers is limited by 8?
>
> thanks,
> vlad
Hi vlad,
Documentation states that a packet (or multiple packets in transmit
segmentation) can span any number of
buffers (and their descriptors) up to a limit of 40 minus WTHRESH minus 2.
Shouldn't there be a test in transmit function that drops properly the
mbufs with a too large number of
segments, while incrementing a statistic; otherwise transmit function
may be locked by the faulty packet without
notification.
thanks
didier
More information about the dev
mailing list