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Date: Sun, 2 Aug 2026 18:35:57 +0800
From: Zorro Lang <zlang@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: fstests@vger.kernel.org, 
	"Martin K. Petersen" <martin.petersen@oracle.com>, Kanchan Joshi <joshi.k@samsung.com>, 
	Anuj Gupta <anuj20.g@samsung.com>, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/4] common/scsi_debug: don't slow down I/O
Message-ID: <am8Yg5NMbLuIOfBd@zlang-mailbox>
Mail-Followup-To: Christoph Hellwig <hch@lst.de>, fstests@vger.kernel.org, 
	"Martin K. Petersen" <martin.petersen@oracle.com>, Kanchan Joshi <joshi.k@samsung.com>, 
	Anuj Gupta <anuj20.g@samsung.com>, linux-scsi@vger.kernel.org
References: <20260723142856.108193-1-hch@lst.de>
 <20260723142856.108193-2-hch@lst.de>
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In-Reply-To: <20260723142856.108193-2-hch@lst.de>

On Thu, Jul 23, 2026 at 04:28:44PM +0200, Christoph Hellwig wrote:
> scsi_debug by defaults delays I/O and doesn't support multi-page I/O.
> Flipping these defaults speed up each test using scsi_debug by more than
> an order of magnitute on my test systems.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  common/scsi_debug | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/common/scsi_debug b/common/scsi_debug
> index c3fe7be623fa..91665547bc0c 100644
> --- a/common/scsi_debug
> +++ b/common/scsi_debug
> @@ -59,7 +59,9 @@ _get_scsi_debug_dev()
>  		let physical=physical/2
>  		let phys_exp=phys_exp+1
>  	done
> -	opts="sector_size=$logical physblk_exp=$phys_exp lowest_aligned=$unaligned dev_size_mb=$size $@"
> +	opts="sector_size=$logical physblk_exp=$phys_exp"
> +	opts="${opts} lowest_aligned=$unaligned dev_size_mb=$size"
> +	opts="${opts} delay=0 clustering=1 $@"
>  	echo "scsi_debug options $opts" >> $seqres.full
>  	modprobe scsi_debug $opts

While this is syntactically correct, especially when leaving $opts unquoted.
But as this patch is trying to to improve code readability, so how about:

local opts=(
    "sector_size=$logical"
    "physblk_exp=$phys_exp"
    "lowest_aligned=$unaligned"
    "dev_size_mb=$size"
    "delay=0"
    "clustering=1"
)
opts+=("$@")
echo "scsi_debug options ${opts[*]}" >> $seqres.full
modprobe scsi_debug "${opts[@]}"

Thanks,
Zorro

>  	[ $? -eq 0 ] || _fail "scsi_debug modprobe failed"
> -- 
> 2.53.0
>