[stgt] [PATCH RESEND 0/3] Add SCSI cmd statistics per ITL nexus

ronnie sahlberg ronniesahlberg at gmail.com
Wed Jul 18 00:55:59 CEST 2012

Hi Alexander

On Wed, Jul 18, 2012 at 8:47 AM, Alexander Nezhinsky
<nezhinsky at gmail.com> wrote:
> On Wed, Jul 18, 2012 at 1:31 AM, ronnie sahlberg
> <ronniesahlberg at gmail.com> wrote:
>> Hi,
>> Since all media access commands take a 5 bit groupnumber for this
>> specific purpose
>> we should make sure that the stats are collected into 32 different
>> buckets depending of the group number in the CDB
> It's a good point and we may decide to do so, but it seems to be mandatory
> only if presented in "Statistics and Performance" page.
> We are presenting it for the target's admin thus it is at least "not a bug"
> to do it without the group number bins.

Sure, not a bug,  but adding the groups would be very nice!
And then, to be standards compliant we should probably add a
StatisticsAndPerformance page too.

> Moreover, collecting cmds to bins should be done *in addition* to the
> current scheme,

Ok. That works.

> and not instead of it, because not all commands have group number.
> Should the other "non-grouped" cmds be collected to a special bin?

I dont know.  the spec seems to give a lot of freedom to the
implementors in this area.
I would say either put all of the non-grouped commands into group #0
or add an extra group, group #32   and put them there.

I dont know what is best there.

Creating a special group #32 would mean that you would not pollute the
data for the reads/writes in group #0
with data from a milion TestUnitReady calls.

> Anyway, let's decide on how we make it fully spec compliant and add this
> group flavor the statistics.


ronnie sahlberg
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