On Thu, Mar 05, 2020 at 12:26:01PM +0100, Jinpu Wang wrote: > We have to admit, the code snip is from null_blk, get_tag function, > not invented by us. > the get_cpu/put_cpu was added to get/save the current cpu_id, which > can be removed around the do-while loop., > we only need to raw_smp_processor_id to get current cpu, we use it > later to pick which connection to use. Be careful copying crazy core code into drivers.. > > You have to do something to provably guarantee the send q cannot > > overflow. send q overflow is defined as calling post_send before a > > poll_cq has confirmed space is available for send. > Shouldn't the cq api handle that already, with IB_POLL_SOFTIRQ, > poll cq is done on very softirq run, so send queue space should be reclaimed > fast enough, with IB_POLL_WORKQUEUE, when cq->com_handler get called, > the ib_cq_poll_work will do the poll_cq, together with extra > send_queue size reserved, > the send queue can not overflow! Somehow that doesn't sound like 'provably guarentee' - that is some statistical argument.. Jason
