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Date: Mon, 20 Oct 2014 10:36:01 +0100
From: Bruce Richardson <bruce.richardson@intel.com>
To: Matthew Hall <mhall@mhcomputing.net>
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Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] "TX WTHRESH must be set to 0 if tx_rs_thresh is
 greater than 1"
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On Sun, Oct 19, 2014 at 10:08:29AM -0700, Matthew Hall wrote:
> 1.7.1 with a few minor clang compatibility patches in the example apps

Rather than trying to tune the results yourself, maybe you could look to 
merge in the following patch set also, to offload responsibility for the 
driver settings to the driver itself.

http://thread.gmane.org/gmane.comp.networking.dpdk.devel/6189

/Bruce

> -- 
> Sent from my mobile device.
> 
> On October 19, 2014 6:46:27 AM PDT, Marc Sune <marc.sune@bisdn.de> wrote:
> >Which DPDK version are you using
> >
> >marc
> >
> >On 19/10/14 00:50, Matthew Hall wrote:
> >> Hello,
> >>
> >> I'm just trying to understand what you're supposed to do about this
> >error to
> >> get the optiomal configuration / performance. The error message and
> >comments
> >> seem like they're designed for Intel ethernet driver hackers not
> >security
> >> hackers like myself! ;-)
> >>
> >> Note: I'm trying out the Intel 82545EM in VirtualBox because the
> >virtio-net
> >> approach didn't work, for reasons I enumerated in some previous
> >mails.
> >>
> >>      /*
> >>       * If rs_bit_thresh is greater than 1, then TX WTHRESH should be
> >>       * set to 0. If WTHRESH is greater than zero, the RS bit is
> >ignored
> >>       * by the NIC and all descriptors are written back after the NIC
> >>       * accumulates WTHRESH descriptors.
> >>       */
> >>      if (tx_conf->tx_thresh.wthresh != 0 && tx_rs_thresh != 1) {
> >>          RTE_LOG(ERR, PMD, "TX WTHRESH must be set to 0 if "
> >>              "tx_rs_thresh is greater than 1. (tx_rs_thresh=%u "
> >>              "port=%d queue=%d)\n", (unsigned int)tx_rs_thresh,
> >>                  (int)dev->data->port_id, (int)queue_idx);
> >>          return -(EINVAL);
> >>      }
> >>
> >> Thanks,
> >> Matthew.
>