On Thu, 12 Nov 2020 13:09:59 -0600 Thomas Falcon wrote:
> Include support for the xmit_more feature utilizing the
> H_SEND_SUB_CRQ_INDIRECT hypervisor call which allows the sending
> of multiple subordinate Command Response Queue descriptors in one
> hypervisor call via a DMA-mapped buffer. This update reduces hypervisor
> calls and thus hypervisor call overhead per TX descriptor.
>
> Signed-off-by: Thomas Falcon <tlfal...@linux.ibm.com>
The common bug with xmit_more is not flushing the already queued
notifications when there is a drop. Any time you drop a skb you need
to check it's not an skb that was the end of an xmit_more train and
if so flush notifications (or just always flush on error).
Looking at the driver e.g. this starting goto:
if (ibmvnic_xmit_workarounds(skb, netdev)) {
tx_dropped++;
tx_send_failed++;
ret = NETDEV_TX_OK;
goto out;
}
Does not seem to hit any flush on its way out AFAICS.
