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Message-ID: <f2c97e860f895613ba81b69c962660b0c712723a.camel@suse.de>
Subject: Re: [PATCH] scsi: core: Log SCSI command age with errors
From:   Martin Wilck <mwilck@suse.de>
To:     Laurence Oberman <loberman@redhat.com>,
        "Milan P. Gandhi" <mgandhi@redhat.com>,
        linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org
Cc:     jejb@linux.ibm.com, martin.petersen@oracle.com
Date:   Mon, 30 Sep 2019 10:42:14 +0200
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On Fri, 2019-09-27 at 13:45 -0400, Laurence Oberman wrote:
> 
> Hi Martin
> 
> Agreed about log extraction, but turning that on with a busy workload
> in a production environment is not practical. We cant do it with
> systems with 1000's of luns and 1000's of IOPS/sec.
> Also second resolution is good enough for the debug we want to see.

I gather that you look at a specific problem where second resolution is
sufficient. For upstream, the generic usefulness should be considered,
and I don't think we can say today that better-than-second resolution
will never be useful, so I still vote for milliseconds.

Wrt the enablement of the option on highly loaded systems, I'm not sure
I understand. You need to enable SCSI logging anyway, don't you? Is it
an issue to have to set 2 sysfs values rather than just one?

Regards,
Martin

> 
> Regards
> Laurence
>