On 11/26/20 2:48 AM, Tyrel Datwyler wrote:
Recent updates in pHyp Firmware and VIOS releases provide new infrastructure
towards enabling Subordinate Command Response Queues (Sub-CRQs) such that each
Sub-CRQ is a channel backed by an actual hardware queue in the FC stack on the
partner VIOS. Sub-CRQs are registered with the firmware via hypercalls and then
negotiated with the VIOS via new Management Datagrams (MADs) for channel setup.
This initial implementation adds the necessary Sub-CRQ framework and implements
the new MADs for negotiating and assigning a set of Sub-CRQs to associated VIOS
HW backed channels. The event pool and locking still leverages the legacy single
queue implementation, and as such lock contention is problematic when increasing
the number of queues. However, this initial work demonstrates a 1.2x factor
increase in IOPs when configured with two HW queues despite lock contention.
Why do you still hold the hold lock during submission?
An initial check on the submission code path didn't reveal anything
obvious, so it _should_ be possible to drop the host lock there.
Or at least move it into the submission function itself to avoid lock
contention. Hmm?
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
