[SPDK] Re: vhost is destroyed many times when starting vhost device

Hi, Feng

Thanks for your digging on this scenario. Yes, it is really a problem on which we should consider more.

I looked into your patch. But I just think you missed the situation if the backend bdev is hot removed, seems the dummy_io_channel will prevent the removal process.

 --Thanks
From Xiaodong

-----Original Message-----
From: Li Feng <fengli(a)smartx.com> 
Sent: Friday, April 24, 2020 10:44 PM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: [SPDK] Re: vhost is destroyed many times when starting vhost device

Hi,
I have submitted a patch[1] to partially fix this issue.
Any suggestions?
After applying this patch, the log of call io_setup/io_destroy will be gone.

[1]: https://review.spdk.io/gerrit/c/spdk/spdk/+/2020

Thanks,

Feng Li

Li Feng <fengli(a)smartx.com> 于2020年4月23日周四 下午8:29写道：
>
> Hi,
>
> In rte_vhost_compat.c, spdk_extern_vhost_pre_msg_handler will call 
> destroy_device when some conditions meet.
>
> I tested and found when a vhost-blk setup, the vhost device will be 
> destroyed 9 times.
> And the bdev(no matter which type) will be affected. I'm using the aio 
> bdev, and the io_setup/io_destroy will be called 9 times when a disk 
> is inserted to a VM.
>
> My concern is:
> Is there any solution to reduce the call times(at least: disks nums * 9)?
> The call will slow down the VM boot time if VM has multiple disks.
> There are some  related logs:
>
> Starting SPDK v20.01-pre git sha1 93eecf627 / DPDK 19.11.0 initialization...
> [ DPDK EAL parameters: spdk_tgt --no-shconf -c 1 -m 1
> --log-level=lib.eal:6 --log-level=lib.cryptodev:5 --log-level=user1:6 
> --iova-mode=pa --base-virtaddr=0x200000000000 --match-allocations
> --file-prefix=spdk_pid2004865 ]
> EAL: No available hugepages reported in hugepages-1048576kB
> app.c: 645:spdk_app_start: *NOTICE*: Total cores available: 1
> reactor.c: 346:_spdk_reactor_run: *NOTICE*: Reactor started on core 0
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 174:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 193:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
> rte_vhost_compat.c: 225:spdk_extern_vhost_pre_msg_handler: *ERROR*:
> destroy device
> rte_vhost_compat.c: 130:stop_device: *ERROR*: call stop_device
> bdev_aio.c: 581:bdev_aio_group_destroy_cb: *ERROR*:  call io_destroy
> bdev_aio.c: 563:bdev_aio_group_create_cb: *ERROR*:  call io_setup
>
> Thanks,
>
> Feng Li

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