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From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "martin.petersen@oracle.com" <martin.petersen@oracle.com>
CC: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"James.Bottomley@HansenPartnership.com"
	<James.Bottomley@HansenPartnership.com>, "linux-block@vger.kernel.org"
	<linux-block@vger.kernel.org>, "osandov@fb.com" <osandov@fb.com>,
	"hare@suse.com" <hare@suse.com>, "axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH v4 10/10] scsi: Implement blk_mq_ops.show_rq()
Date: Mon, 24 Apr 2017 21:49:37 +0000
Message-ID: <1493070575.3394.19.camel@sandisk.com>
References: <20170421234026.18970-1-bart.vanassche@sandisk.com>
	 <20170421234026.18970-11-bart.vanassche@sandisk.com>
	 <yq1k269ij5f.fsf@oracle.com>
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On Mon, 2017-04-24 at 17:35 -0400, Martin K. Petersen wrote:
> > Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
> > in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.
>=20
> Why not use SCSI tracing if you are interested in these?

Hello Martin,

SCSI tracing has to be enabled before a test is started, produces a huge am=
ount
of data, and deriving state information from a huge trace is far from easy.=
 The
information in debugfs provides an easy to read overview of the current sta=
te
without having to analyze megabytes of traces, without introducing any slow=
down
and without having to enable any tracing mechanism from beforehand.

Bart.=