From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [patch 5/5] block: use a driver-specific handler for
 the "inflight" value
Date: Wed, 14 Nov 2018 07:18:48 -0800
Message-ID: <20181114151848.GA22138@infradead.org>
References: <20181106213858.391264280@debian-a64.vm>
	<20181108145240.GA20087@infradead.org>
	<20181108170701.GA29107@redhat.com>
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To: Mike Snitzer <snitzer@redhat.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org, Christoph Hellwig <hch@infradead.org>, dm-devel@redhat.com, Mikulas Patocka <mpatocka@redhat.com>, "Alasdair G. Kergon" <agk@redhat.com>
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On Thu, Nov 08, 2018 at 12:07:01PM -0500, Mike Snitzer wrote:
> Discussed doing that with Jens and reported as much here:
> 
> https://www.redhat.com/archives/dm-devel/2018-November/msg00068.html
> 
> And Jens gave additional context for why yet another attempt to switch
> block core's in_flight to percpu counters is doomed (having already been
> proposed and rejected twice):
> 
> https://www.redhat.com/archives/dm-devel/2018-November/msg00071.html
> 
> And yes, definitely should've cc'd linux-block (now added).

So how is dm different from the the other 3 handful of drivers using
the make_request interface that the per-cpu counters work for dm and
not the others?