[openib-general] Re: [PATCH] TX/RX_RING_SIZE as loadable parameters

[Talpey, Thomas]

At 08:59 AM 3/7/2006, Michael S. Tsirkin wrote:
>How about we take the ring buffer size from dev->tx_queue_len?
>
>Round it up to the previous power of 2, for simplicity.
>IPOIB_TX_RING_SIZE will then be just the default value, so it can
>stay hardcoded. Make the RX queue say twice the number, and keep it per device.
>
>This way I think the user can both view, and set, these values with the
>standard "ip" command.

Makes sense to me! And it certainly meets the requirement of
per-interface tunables, using standard interfaces (ifconfig).

Remember though, tx_queue_len is only somewhat proportional
to the hardware tx queue. Technically, it's the send backlog
for use when the hardware queue is full. It's often smaller for
faster hardware.

OTOH, receive rings are usually *larger* for faster hardware.
Might be worth thinking these relationships through...

Tom.