Messages in this thread | | | Date | Mon, 3 Apr 2023 01:26:35 -0400 | Subject | Re: [PATCH v3 11/11] scsi: scsi_debug: Drop sdebug_queue | From | Douglas Gilbert <> |
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On 2023-03-27 03:43, John Garry wrote: > It's easy to get scsi_debug to error on throughput testing when we have > multiple shosts: > > $ lsscsi > [7:0:0:0] disk Linux scsi_debug 0191 > [0:0:0:0] disk Linux scsi_debug 0191 > > $ fio --filename=/dev/sda --filename=/dev/sdb --direct=1 --rw=read --bs=4k > --iodepth=256 --runtime=60 --numjobs=40 --time_based --name=jpg > --eta-newline=1 --readonly --ioengine=io_uring --hipri --exitall_on_error > jpg: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=io_uring, iodepth=256 > ... > fio-3.28 > Starting 40 processes > [ 27.521809] hrtimer: interrupt took 33067 ns > [ 27.904660] sd 7:0:0:0: [sdb] tag#171 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK cmd_age=0s > [ 27.904660] sd 0:0:0:0: [sda] tag#58 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK cmd_age=0s > fio: io_u error [ 27.904667] sd 0:0:0:0: [sda] tag#58 CDB: Read(10) 28 00 00 00 27 00 00 01 18 00 > on file /dev/sda[ 27.904670] sd 0:0:0:0: [sda] tag#62 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK cmd_age=0s > > The issue is related to how the driver manages submit queues and tags. A > single array of submit queues - sdebug_q_arr - with its own set of tags is > shared among all shosts. As such, for occasions when we have more than one > shost it is possible to overload the submit queues and run out of tags. > > The struct sdebug_queue is to manage tags and hold the associated > queued command entry pointer (for that tag). > > Since the tagset iters are now used for functions like > sdebug_blk_mq_poll(), there is no need to manage these queues. Indeed, > blk-mq already provides what we need for managing tags and queues. > > Drop sdebug_queue and all its usage in the driver. > > Signed-off-by: John Garry <john.g.garry@oracle.com> Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Thanks.
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