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From: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
To: device-mapper development <dm-devel@redhat.com>,
	Hannes Reinecke <hare@suse.de>
Cc: Mikulas Patocka <mpatocka@redhat.com>, Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH] dm-table: delayed cleanup for dm_table_destroy()
Date: Wed, 21 Mar 2012 14:34:37 +0900	[thread overview]
Message-ID: <4F69686D.8010208@ce.jp.nec.com> (raw)
In-Reply-To: <4F68A3D8.40005@suse.de>

Hi Hannes,

On 03/21/12 00:35, Hannes Reinecke wrote:
> The actual problem I'm trying to track down is that I'm seeing an
> excessive duration for the 'resume' dm ioctl after a table update.
> I've got reports where the ioctl can take up to several seconds.
> Which (as this is multipath) causes an extremely erratic behaviour.
> 
> And the 'msleep' here is one of the obvious culprits.
> 
> But I'll continue debugging, maybe I'll find something else.

Did you track down which part of the resume ioctl took long?

If table is updated and the device is not yet suspended,
resume ioctl itself suspends the device.
And dm_suspend() could take long depending on lower devices
as it waits for already-submitted I/Os to return to dm.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation

      parent reply	other threads:[~2012-03-21  5:34 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-19 15:53 [PATCH] Device-mapper misc cleanup Hannes Reinecke
2012-03-19 15:53 ` [PATCH] dm: zero out bi_end_io on remapping failure Hannes Reinecke
2012-03-19 15:53   ` [PATCH] dm-table: simplify call to free_devices() Hannes Reinecke
2012-03-19 15:53     ` [PATCH] dm-table: delayed cleanup for dm_table_destroy() Hannes Reinecke
2012-03-19 21:45       ` Mikulas Patocka
2012-03-20 15:35         ` Hannes Reinecke
2012-03-20 19:43           ` Mike Snitzer
2012-03-21  1:20             ` Mikulas Patocka
2012-03-21  1:24           ` [PATCH] " Mikulas Patocka
2012-03-21  5:34           ` Jun'ichi Nomura [this message]

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