linux-kernel - Re: SCSI sr driver: parallel writes to optical serialized which hurts performance (sr

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Message-ID: <20160306020613.GA31413@animx.eu.org>
Date:	Sat, 5 Mar 2016 21:06:13 -0500
From:	Wakko Warner <wakko@...mx.eu.org>
To:	Johan de Jong <jrdejong@...il.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Schmitt <scdbackup@....net>
Subject: Re: SCSI sr driver: parallel writes to optical serialized which
 hurts performance (sr_mutex)

Johan de Jong wrote:
> Hi Wakko,
> 
> If I remember correctly I did see you commenting on discussions on
> either the Otto Meta patch, or another that proposed to remove the
> mutex entirely. I was unaware of any others.

I received the last set of patches from Tim more than a year ago.  I wasn't
using a system with multiple drives other than my 3.3.0 box.  Last year
around november I gathered some more drives and put them in another system
and I decided to test the patches.  I sent a report back to the list back in
november 2015 (maybe october) about the success.

> Do you have more information on why this never resulted in a succesful
> concerted effort to get a patch in the kernel tree? Do the patches
> have drawbacks or have they never been submitted properly? If the
> latter, we might endeavor it?

No, sorry.  I'm just a user.  I haven't had any crashes with the patches.
I'd like to see the patches go in, I'm tired of patching every new kernel.
I'm running the ones from Tim on 2 machines.  One machine has the dvd
burners (exported as iscsi targets) and the other machine connects to it. 
The patches have to be on both machines for it to work (I assume).  I'm able
to burn at 16x to 3 burners over iscsi at the same time.  I've burned many
discs this way with out any issues (other than bad media).

Just FYI: The computer with the burners is running 4.4.1 and the iscsi
initiator is 3.12.52.

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.