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From: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
To: "dsterba@suse.cz" <dsterba@suse.cz>
Cc: David Sterba <dsterba@suse.com>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH] btrfs: scrub: per-device bandwidth control
Date: Wed, 19 May 2021 15:32:48 +0000	[thread overview]
Message-ID: <PH0PR04MB74165244AB3C1AC48DF8DF379B2B9@PH0PR04MB7416.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20210519142612.GW7604@twin.jikos.cz

On 19/05/2021 16:28, David Sterba wrote:
> On Wed, May 19, 2021 at 06:53:54AM +0000, Johannes Thumshirn wrote:
>> On 18/05/2021 16:52, David Sterba wrote:
>> I wonder if this interface would make sense for limiting balance
>> bandwidth as well?
> 
> Balance is not contained to one device, so this makes the scrub case
> easy. For balance there are data and metadata involved, both read and
> write accross several threads so this is really something that the
> cgroups io controler is supposed to do.
> 

For a user initiated balance a cgroups io controller would work well, yes.
But for having a QoS mechanism to decide when it's a good time to rebalance
one or more block groups, i.e. with a zoned file system or when we switch
to auto-balance in the future I'm not sure if cgroups would help us much
in this case.

But this can be my lack of knowledge as well.

  reply	other threads:[~2021-05-19 15:32 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18 14:49 [PATCH] btrfs: scrub: per-device bandwidth control David Sterba
2021-05-18 16:52 ` Holger Hoffstätte
2021-05-18 20:46   ` David Sterba
2021-05-18 20:15 ` waxhead
2021-05-18 21:06   ` David Sterba
2021-05-19  6:53 ` Johannes Thumshirn
2021-05-19 14:26   ` David Sterba
2021-05-19 15:32     ` Johannes Thumshirn [this message]
2021-05-19 16:20       ` Graham Cobb
2021-05-20 12:41         ` David Sterba
2021-05-21  7:18         ` Zygo Blaxell
2021-05-21  9:55           ` Graham Cobb
2021-05-20 12:28       ` David Sterba
2021-05-20  7:43 ` Geert Uytterhoeven
2021-05-20 12:55   ` David Sterba
2021-05-20 13:04     ` Geert Uytterhoeven
2021-05-20 13:14   ` Arnd Bergmann
2021-05-20 13:26     ` Geert Uytterhoeven
2021-05-21 15:16     ` David Sterba
2021-05-21 15:38       ` Geert Uytterhoeven

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