Date: Mon, 8 Jul 2013 08:21:58 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: Kent Overstreet <kmo@daterainc.com>, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org, tj@kernel.org, sfr@canb.auug.org.au,
        andi@firstfloor.org, oleg@redhat.com, mingo@redhat.com,
        axboe@kernel.dk, target-devel <target-devel@vger.kernel.org>
Subject: Re: [PATCH v3] lib/idr.c rewrite, percpu ida/tag allocator
Message-ID: <20130708052158.GA6938@redhat.com>
References: <1373087301-23730-1-git-send-email-kmo@daterainc.com>
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 <20130707114852.GA5463@redhat.com>
 <1373249375.7397.139.camel@haakon3.risingtidesystems.com>
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On Sun, Jul 07, 2013 at 07:09:35PM -0700, Nicholas A. Bellinger wrote:
> On Sun, 2013-07-07 at 14:48 +0300, Michael S. Tsirkin wrote:
> > On Sat, Jul 06, 2013 at 03:59:06PM -0700, Nicholas A. Bellinger wrote:
> > > On Fri, 2013-07-05 at 22:08 -0700, Kent Overstreet wrote:
> > > > Previous posting: http://thread.gmane.org/gmane.linux.kernel/1511216
> > > > 
> > > > The only real change since the last version is that I've reworked the
> > > > new ida implementation to not use one giant allocation - it's still
> > > > logically one big arary, but it's implemented as an array of arrays.
> > > > 
> > > > With that, it scales up to INT_MAX allocated ids just fine. Benchmarks
> > > > are included in that patch.
> > > > 
> > > > Patch series is available in my git repo:
> > > > git://evilpiepirate.org/~kent/linux-bcache.git idr
> > > > 
> > > > Andrew, want to pick this up for 3.12?
> > > 
> > > Just FYI that the target-pending/target-per-cpu-ida branch utilizing
> > > per-cpu ida logic for vhost-scsi has been rebased to include this latest
> > > series.  Thanks Kent!
> > > 
> > > Andrew, what are your plans for this..?
> > > 
> > > Would you consider allowing this series be merged through target-pending
> > > in order to allow us to start taking advantage of per-cpu ida tag
> > > pre-allocation optimizations for v3.12 target code..? 
> > > 
> > > Another option would be to merge the per-cpu ida specific piece now for
> > > v3.11 for which the risk is low given it doesn't touch any existing
> > > code, and then include Kent's full idr rewrite separately as v3.12 item.
> > > 
> > > WDYT..?
> > 
> > Takes as is, this conflicts with cleanup patches by Asias in vhost-next
> > that I was going to send to Linus for 3.11.
> 
> So the proposed vhost-scsi per-cpu ida/tag pre-allocation changes should
> be considered v3.12 items.
> 
> > Merging new target code for 3.11 and vhost code for 3.12
> > helps keep the dependencies simple, so I'm all for it.
> > 
> 
> My point above is that having (at least) Kent's per-cpu ida code merged
> for v3.11 would make it easier to move forward during the v3.12 cycle on
> per-cpu ida/tag conversions for vhost-scsi + other target fabric
> drivers.
> 
> --nab

Exactly. I think it's a good idea, too.

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