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Message-ID: <e0179895-5d06-4c47-98f2-635175a05cf7@oracle.com>
Date: Mon, 8 Apr 2024 13:30:07 +0100
From: John Garry <john.g.garry@...cle.com>
To: Lei Chen <lei.chen@...rtx.com>,
Kashyap Desai
<kashyap.desai@...adcom.com>,
Sumit Saxena <sumit.saxena@...adcom.com>,
Shivasharan S <shivasharan.srikanteshwara@...adcom.com>,
Chandrakanth patil <chandrakanth.patil@...adcom.com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>
Cc: megaraidlinux.pdl@...adcom.com, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] scsi: megaraid_sas: make module parameter
scmd_timeout writable
On 08/04/2024 11:05, Lei Chen wrote:
> When an scmd times out, block layer calls megasas_reset_timer to
> make further decisions. scmd_timeout indicates when an scmd is really
> timed-out.
What does really timed-out mean?
> If we want to make this process more fast, we can decrease
> this value. This patch allows users to change this value in run-time.
>
> Signed-off-by: Lei Chen <lei.chen@...rtx.com>
> ---
> drivers/scsi/megaraid/megaraid_sas_base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index 3d4f13da1ae8..2a165e5dc7a3 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -91,7 +91,7 @@ module_param(dual_qdepth_disable, int, 0444);
> MODULE_PARM_DESC(dual_qdepth_disable, "Disable dual queue depth feature. Default: 0");
>
> static unsigned int scmd_timeout = MEGASAS_DEFAULT_CMD_TIMEOUT;
> -module_param(scmd_timeout, int, 0444);
> +module_param(scmd_timeout, int, 0644);
> MODULE_PARM_DESC(scmd_timeout, "scsi command timeout (10-90s), default 90s. See megasas_reset_timer.");
>
> int perf_mode = -1;
I don't know why megaraid_sas has special handling here (and bypasses
SCSI midlayer).
If the host is overloaded and you get a time-out as a command simply
could not be handled in time, can you alternatively try reducing the
scsi device queue depth?
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