RE: [PATCH RFC v6 08/10] megaraid_sas: switch fusion adapters to MQ

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



>
> So I tested this on hisi_sas with x12 SAS SSDs, and performance with "mq-
> deadline" is comparable with "none" @ ~ 2M IOPs. But after a while
> performance drops alot, to maybe 700K IOPS. Do you have a similar
> experience?

I am using mq-deadline only for HDD. I have not tried on SSD since it is not
useful scheduler for SSDs.

I noticed that when I used mq-deadline, performance drop starts if I have
more number of drives.
I am running <fio> script which has 64 Drives, 64 thread and all treads are
bound to local numa node which has 36 logical cores.
I noticed that lock contention is in " dd_dispatch_request". I am not sure
why there is a no penalty of same lock in nr_hw_queue  = 1 mode.

static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
        struct deadline_data *dd = hctx->queue->elevator->elevator_data;
        struct request *rq;

        spin_lock(&dd->lock);
        rq = __dd_dispatch_request(dd);
        spin_unlock(&dd->lock);

        return rq;
}

Here is perf report -

-    1.04%     0.99%  kworker/18:1H+k  [kernel.vmlinux]  [k]
native_queued_spin_lock_slowpath
     0.99% ret_from_fork
    -   kthread
      - worker_thread
         - 0.98% process_one_work
            - 0.98% __blk_mq_run_hw_queue
               - blk_mq_sched_dispatch_requests
                  - 0.98% blk_mq_do_dispatch_sched
                     - 0.97% dd_dispatch_request
                        + 0.97% queued_spin_lock_slowpath
+    1.04%     0.00%  kworker/18:1H+k  [kernel.vmlinux]  [k]
queued_spin_lock_slowpath
+    1.03%     0.95%  kworker/19:1H-k  [kernel.vmlinux]  [k]
native_queued_spin_lock_slowpath
+    1.03%     0.00%  kworker/19:1H-k  [kernel.vmlinux]  [k]
queued_spin_lock_slowpath
+    1.02%     0.97%  kworker/20:1H+k  [kernel.vmlinux]  [k]
native_queued_spin_lock_slowpath
+    1.02%     0.00%  kworker/20:1H+k  [kernel.vmlinux]  [k]
queued_spin_lock_slowpath
+    1.01%     0.96%  kworker/21:1H+k  [kernel.vmlinux]  [k]
native_queued_spin_lock_slowpath


>
> Anyway, I'll have a look.
>
> Thanks,
> John



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]

  Powered by Linux