git: 7d4c444374d5 - main - Bump CTL block backend threads from 14 to 32 per LUN.

[Rodney W. Grimes]

> The branch main has been updated by mav:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=7d4c444374d53e54ce197138df64bf40c1fb05a3
> 
> commit 7d4c444374d53e54ce197138df64bf40c1fb05a3
> Author:     Alexander Motin <mav at FreeBSD.org>
> AuthorDate: 2021-02-23 15:58:56 +0000
> Commit:     Alexander Motin <mav at FreeBSD.org>
> CommitDate: 2021-02-23 16:03:32 +0000
> 
>     Bump CTL block backend threads from 14 to 32 per LUN.
>     
>     This makes random read benchmarks look better on a wide ZFS pools.
>     I am not sure where the original value goes from, but it is there
>     for too long now.

I would think this should be bounded by the number of cores/threads
in the system.  What happens on a 4 thread system with this value?


>     
>     MFC after:      1 week
> ---
>  sys/cam/ctl/ctl_backend_block.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sys/cam/ctl/ctl_backend_block.c b/sys/cam/ctl/ctl_backend_block.c
> index 7ec8e32f7338..f50e47a2a6c1 100644
> --- a/sys/cam/ctl/ctl_backend_block.c
> +++ b/sys/cam/ctl/ctl_backend_block.c
> @@ -226,7 +226,7 @@ struct ctl_be_block_io {
>  
>  extern struct ctl_softc *control_softc;
>  
> -static int cbb_num_threads = 14;
> +static int cbb_num_threads = 32;
>  SYSCTL_NODE(_kern_cam_ctl, OID_AUTO, block, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
>  	    "CAM Target Layer Block Backend");
>  SYSCTL_INT(_kern_cam_ctl_block, OID_AUTO, num_threads, CTLFLAG_RWTUN,
> 

-- 
Rod Grimes                                                 rgrimes at freebsd.org