From: Alasdair G Kergon <agk@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Guangliang Zhao <gzhao@suse.com>,
linux-kernel@vger.kernel.org, dm-devel@redhat.com,
lucienchao@gmail.com, "Alasdair G. Kergon" <agk@redhat.com>
Subject: Re: [PATCH 2/2] mirror throttling
Date: Fri, 15 Feb 2013 00:53:21 +0000 [thread overview]
Message-ID: <20130215005321.GK24130@agk-dp.fab.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1301090044170.29917@file.rdu.redhat.com>
On Wed, Jan 09, 2013 at 12:44:38AM -0500, Mikulas Patocka wrote:
> We maintain a history of kcopyd usage in variables io_period and
> total_period. The actual kcopyd activity is "(100 * io_period /
> total_period)" percent of time. If we exceed user-defined percentage
> threshold, we sleep.
Well, I'm going to take this pair of patches for now.
Some people do need this throttling today and this seems to me to be a
decent and simple way to give them a lever to deal with the problem.
I'm not proposing we expose this through LVM or other userspace tools at
this stage: people who need it should tune it directly through sysfs.
If need be, we can revisit this in future either by refining the
algorithm or making it adjustable per-device rather than per-module.
(Or by re-vamping kcopyd itself...)
The current version is:
http://people.redhat.com/agk/patches/linux/editing/dm-kcopyd-introduce-configurable-throttling.patch
Alasdair
prev parent reply other threads:[~2013-02-15 0:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-07 10:02 [PATCH 0/3 v3] add resync speed control for dm-raid1 Guangliang Zhao
2013-01-07 10:02 ` [PATCH 1/3 v3] dm raid1: " Guangliang Zhao
2013-01-07 10:02 ` [PATCH 2/3 v3] dm raid1: add interface to set resync speed Guangliang Zhao
2013-01-07 10:02 ` [PATCH 3/3 v3] dm raid1: add interface to get " Guangliang Zhao
2013-01-09 5:43 ` [dm-devel] [PATCH 0/3 v3] add resync speed control for dm-raid1 Mikulas Patocka
2013-01-16 8:21 ` Guangliang Zhao
2013-01-23 1:44 ` Mikulas Patocka
2013-01-23 4:20 ` NeilBrown
2013-02-06 0:24 ` Mikulas Patocka
2013-01-09 5:44 ` [PATCH 1/2] mirror throttling Mikulas Patocka
2013-01-09 5:44 ` [PATCH 2/2] " Mikulas Patocka
2013-02-15 0:53 ` Alasdair G Kergon [this message]
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