Re: [dpdk-dev] l2fwd not working on PF while working on VF

[Chris Wright <chrisw@redhat.com>]

* Richardson, Bruce (bruce.richardson@intel.com) wrote:
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Tomasz K
> > Sent: Wednesday, April 09, 2014 3:04 PM
> > To: dev
> > Subject: [dpdk-dev] l2fwd not working on PF while working on VF
> > 
> > Dear All
> > 
> > I have a setup with Intel 82576 DPDK NIC.
> > For one of the available DPDK ports i have created 8 VFs using igb_uio based on
> > steps presented in programmers guide. Some of them are attached to VM, some
> > maybe used on host
> > 
> > After some tests with l2fwd application i found out that it is not working for PF,
> > but works perfectly for any VF (both on host and in VM).
>
> How many queues are being allocated to each VF? According to the datasheet, the 82576 NIC has only got 16 RX and TX queues, so if you have 8 VF's with 2 RX and TX queues allocated to each, you may have no remaining queues left for the PF to use on the host.

BTW, Linux driver caps VFs at 7 for this reason (#include <do drivers in
kernel rant>).  Any reason not to do this w/ igb_uio...e.g.

thanks,
-chris
---
From: Chris Wright <chrisw@redhat.com>
Subject: [PATCH] igb_uio: cap max VFs at 7 to reserve one for PF

To keep from confusing users, cap max VFs at 7, despite PCI SR-IOV config
space showing a max of 8.  This reserves a queue pair for the PF.

Signed-off-by: Chris Wright <chrisw@redhat.com>
---

 lib/librte_eal/linuxapp/igb_uio/igb_uio.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
index 6db8a4a..096fb01 100644
--- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
+++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
@@ -130,6 +130,12 @@ store_max_vfs(struct device *dev, struct device_attribute *attr,
 	if (0 != strict_strtoul(buf, 0, &max_vfs))
 		return -EINVAL;
 
+	/* reserve a queue pair for PF */
+	if (max_vfs > 7) {
+		dev_warn(&pdev->dev, "Maxixum of 7 VFs per PF, using max\n");
+		max_vfs = 7;
+	}
+
 	if (0 == max_vfs)
 		pci_disable_sriov(pdev);
 	else if (0 == local_pci_num_vf(pdev))