Re: [MPT3SAS bug] wrong queue setting for HDD. drive

[Sreekanth Reddy <sreekanth.reddy@broadcom.com>]

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Ming,

Below referred commit changes apply only for NVMe drives.

Driver sets nomerges & virtual boundary under below if condition. And
the driver sets MPT_TARGET_FLAGS_PCIE_DEVICE bit in
sas_target_priv_data->flags only for NVMe drives.

if (sas_target_priv_data->flags & MPT_TARGET_FLAGS_PCIE_DEVICE) {
           ...
                blk_queue_flag_set(QUEUE_FLAG_NOMERGES,
                                sdev->request_queue);
                blk_queue_virt_boundary(sdev->request_queue,
                                ioc->page_size - 1);
}

on my local setup, I have both SAS HDD and NVMe drives as shown below,

[11:0:20:0]  disk    SEAGATE  ST600MP0005      VS09  /dev/sdz
[11:2:0:0]   disk    NVMe     INTEL SSDPE2MW40 0174  /dev/sdab

and default nomerge setting for these drives is as show below,
/sys/devices/pci0000:80/0000:80:03.0/0000:85:00.0/host11/port-11:0/expander-11:0/port-11:0:19/end_device-11:0:19/target11:0:20/11:0:20:0/block/sdz/queue/nomerges:0
/sys/devices/pci0000:80/0000:80:03.0/0000:85:00.0/host11/target11:2:0/11:2:0:0/block/sdab/queue/nomerges:2

so, for SAS HDD drive default nomerge setting is zero and for NVMe
drive the default nomerge setting is two.

 Thanks,
Sreekanth

On Thu, Jan 28, 2021 at 4:08 AM Ming Lei <ming.lei@redhat.com> wrote:
>
> Hello Guys,
>
> The commit[1] is supposed for NVMe device only, but we found the change is
> actually done on the following mpt3sas HDD. drive:
>
>         #sginfo /dev/sdc
>         INQUIRY response (cmd: 0x12)
>         ----------------------------
>         Device Type                        0
>         Vendor:                    SEAGATE
>         Product:                   ST16000NM002G
>         Revision level:            E003)
>
> So NOMERGES is enabled, and virt boundary limit is applied on this HDD.
> device, and performance drop is observed, can you take a look at the
> issue?
>
>
> [1] commit d1b01d14b7baa8a4bb4c11305c8cca73456b2f7c
> Author: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
> Date:   Tue Oct 31 18:02:33 2017 +0530
>
>     scsi: mpt3sas: Set NVMe device queue depth as 128
>
>     Sets nvme device queue depth, name and displays device capabilities
>
>
>
> Thanks,
> Ming
>

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