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path: root/drivers/infiniband/core/trace.c
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2020-01-07RDMA/core: Trace points for diagnosing completion queue issuesChuck Lever
Sample trace events: kworker/u29:0-300 [007] 120.042217: cq_alloc: cq.id=4 nr_cqe=161 comp_vector=2 poll_ctx=WORKQUEUE <idle>-0 [002] 120.056292: cq_schedule: cq.id=4 kworker/2:1H-482 [002] 120.056402: cq_process: cq.id=4 wake-up took 109 [us] from interrupt kworker/2:1H-482 [002] 120.056407: cq_poll: cq.id=4 requested 16, returned 1 <idle>-0 [002] 120.067503: cq_schedule: cq.id=4 kworker/2:1H-482 [002] 120.067537: cq_process: cq.id=4 wake-up took 34 [us] from interrupt kworker/2:1H-482 [002] 120.067541: cq_poll: cq.id=4 requested 16, returned 1 <idle>-0 [002] 120.067657: cq_schedule: cq.id=4 kworker/2:1H-482 [002] 120.067672: cq_process: cq.id=4 wake-up took 15 [us] from interrupt kworker/2:1H-482 [002] 120.067674: cq_poll: cq.id=4 requested 16, returned 1 ... systemd-1 [002] 122.392653: cq_schedule: cq.id=4 kworker/2:1H-482 [002] 122.392688: cq_process: cq.id=4 wake-up took 35 [us] from interrupt kworker/2:1H-482 [002] 122.392693: cq_poll: cq.id=4 requested 16, returned 16 kworker/2:1H-482 [002] 122.392836: cq_poll: cq.id=4 requested 16, returned 16 kworker/2:1H-482 [002] 122.392970: cq_poll: cq.id=4 requested 16, returned 16 kworker/2:1H-482 [002] 122.393083: cq_poll: cq.id=4 requested 16, returned 16 kworker/2:1H-482 [002] 122.393195: cq_poll: cq.id=4 requested 16, returned 3 Several features to note in this output: - The WCE count and context type are reported at allocation time - The CPU and kworker for each CQ is evident - The CQ's restracker ID is tagged on each trace event - CQ poll scheduling latency is measured - Details about how often single completions occur versus multiple completions are evident - The cost of the ULP's completion handler is recorded Link: https://lore.kernel.org/r/20191218201815.30584.3481.stgit@manet.1015granger.net Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Parav Pandit <parav@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>