From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>,
"Alasdair G. Kergon" <agk@redhat.com>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
axboe@kernel.dk
Subject: Re: [patch 5/5] block: use a driver-specific handler for the "inflight" value
Date: Thu, 8 Nov 2018 12:07:01 -0500 [thread overview]
Message-ID: <20181108170701.GA29107@redhat.com> (raw)
In-Reply-To: <20181108145240.GA20087@infradead.org>
On Thu, Nov 08 2018 at 9:52am -0500,
Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Nov 06, 2018 at 10:35:03PM +0100, Mikulas Patocka wrote:
> > Device mapper was converted to percpu inflight counters. In order to
> > display the correct values in the "inflight" sysfs file, we need a custom
> > callback that sums the percpu counters.
>
> The attribute that calls this is per-partition, while your method
> is per-queue, so there is some impedence mismatch here.
>
> Is there any way you could look into just making the generic code
> use percpu counters?
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).
Mike
next parent reply other threads:[~2018-11-09 2:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181106213858.391264280@debian-a64.vm>
[not found] ` <20181108145240.GA20087@infradead.org>
2018-11-08 17:07 ` Mike Snitzer [this message]
2018-11-14 15:18 ` [patch 5/5] block: use a driver-specific handler for the "inflight" value Christoph Hellwig
2018-11-14 15:34 ` Mike Snitzer
2018-11-14 22:49 ` Mikulas Patocka
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