[stgt] [PATCH] sg-based backing store

[Richard Sharpe]

On Thu, Oct 16, 2008 at 1:53 AM, ronnie sahlberg
<ronniesahlberg at gmail.com> wrote:
> OFF TOPIC :
>
> On Wed, Oct 8, 2008 at 5:14 PM, FUJITA Tomonori
> <fujita.tomonori at lab.ntt.co.jp> wrote:
>>
>> My point is that the performance of read-world workload benchmark like
>> dbench are relevant for the users than the performances of sequential
>> accesses.
>
>
> Funny you should mention DBENCH ( http://dbench.samba.org ).
> I recently added a NFS backend so that dbench can generate raw NFS
> traffic using "nfs-style" loadfiles. With the ability to take a NFS
> network trace and convert into one such loadfile automatically.
>
> I also recently added a SCSI backend to dbench (though it only handles
> READ10 and TESTUNITREADY commands so far) with the intent of being
> able to trace from a kernel the set of all SCSI operations perfromed
> durign some operation and then use "dbench -B scsi" to replay the
> exact same set of commands.
> My vision is that this could then be used to compare different devices
> how they operate on specific kinds of workloads.
> Maybe one "loadfile" that records and replays all SCSI i/o that goes
> to a device while one is recompiling a kernel,    while operating on a
> very large picture in GIMP, reading a very large document into
> openoffice, etc etc.

Hmmm, it struck me recently that one could write a simple filter SCSI
LLD that interposes itself between a real LLD and the SCSI ML and
captures all CDBs and some of the data on the way through and makes it
available for a capture program in the same way as the packet capture
stuff works.

In some ways, this would be more convenient than using iSCSI ...

-- 
Regards,
Richard Sharpe
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