On Mon, 29 May 2017 15:42:16 +0200
Gaetan Rivet <gaetan.ri...@6wind.com> wrote:
> +Fail-safe poll mode driver library
> +==================================
> +
> +The Fail-safe poll mode driver library (**librte_pmd_failsafe**) is a virtual
> +device that allows using any device supporting hotplug (sudden device removal
> +and plugging on its bus), without modifying other components relying on such
> +device (application, other PMDs).
What about the case of Hyper-V where the components of the Fail Safe PMD may
arrive later. An example would be a NFV server that starts on boot. The
synthetic
device will be present at boot, but the associated VF device may be plugged
in later (by checking SR-IOV on host console) or removed (by unchecking).
There doesn't appear to be a way to manage slave devices that get added
and removed through CLI management model.
> +Using the Fail-safe PMD from the EAL command line
> +-------------------------------------------------
> +
> +The Fail-safe PMD can be used like most other DPDK virtual devices, by
> passing a
> +``--vdev`` parameter to the EAL when starting the application. The device
> name
> +must start with the *net_failsafe* prefix, followed by numbers or letters.
> This
> +name must be unique for each device. Each fail-safe instance must have at
> least one
> +sub-device, up to ``RTE_MAX_ETHPORTS-1``.
> +
> +A sub-device can be any legal DPDK device, including possibly another
> fail-safe
> +instance.
Configuring fail-safe (or any other device) from command line is difficult in a
real
world application. The EAL command line is difficult API to manipulate
programmatically.
Why not have a real API?
> +static int
> +fs_link_update(struct rte_eth_dev *dev,
> + int wait_to_complete)
> +{
> + struct sub_device *sdev;
> + uint8_t i;
> + int ret;
> +
> + FOREACH_SUBDEV_ST(sdev, i, dev, DEV_ACTIVE) {
> + DEBUG("Calling link_update on sub_device %d", i);
> + ret = (SUBOPS(sdev, link_update))(ETH(sdev), wait_to_complete);
> + if (ret && ret != -1) {
> + ERROR("Link update failed for sub_device %d with error
> %d",
> + i, ret);
> + return ret;
> + }
> + }
> + if (TX_SUBDEV(dev)) {
> + struct rte_eth_link *l1;
> + struct rte_eth_link *l2;
> +
> + l1 = &dev->data->dev_link;
> + l2 = Ð(TX_SUBDEV(dev))->data->dev_link;
> + if (memcmp(l1, l2, sizeof(*l1))) {
> + *l1 = *l2;
> + return 0;
> + }
> + }
> + return -1;
> +}
memcmp here is a potential problem since rte_eth_link maybe padded and have
holes.
Why compare anyway? if *l1 == *l2 the assignment would be a nop.
What if links are down?
> +static void
> +fs_stats_get(struct rte_eth_dev *dev,
> + struct rte_eth_stats *stats)
> +{
> + memset(stats, 0, sizeof(*stats));
memset here is unnecessary, already done by rte_eth_stats_get
