From: NeilBrown <neilb@suse.de>
To: stan@hardwarefreak.com
Cc: Christoph Hellwig <hch@infradead.org>,
linux-raid@vger.kernel.org, "xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: md-RAID5/6 stripe_cache_size default value vs performance vs memory footprint
Date: Fri, 27 Dec 2013 09:14:07 +1100 [thread overview]
Message-ID: <20131227091407.2ac401d1@notabene.brown> (raw)
In-Reply-To: <52BBF5B0.8020206@hardwarefreak.com>
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On Thu, 26 Dec 2013 03:24:00 -0600 Stan Hoeppner <stan@hardwarefreak.com>
wrote:
> On 12/26/2013 2:55 AM, Christoph Hellwig wrote:
> > On Sat, Dec 21, 2013 at 05:18:42AM -0600, Stan Hoeppner wrote:
> >> The powers that be, Linus in particular, are not fond of default
> >> settings that create a lot of kernel memory structures. The default
> >> md-RAID5/6 stripe_cache-size yields 1MB consumed per member device.
> >
> > The default sizing is stupid as it basically makes RAID unusable out
> > of the box, I always have to fix that up, as well as a somewhat
> > reasonable chunk size for parity RAID to make it usable. I'm also
> > pretty sure I complained about it at least once a while ago, but never
> > got a reply.
>
> IIRC you Dave C. and myself all voiced criticism after the default chunk
> size was changed from 64KB to 512KB. I guess we didn't make a strong
> enough case to have it reduced, or maybe didn't use the right approach.
>
> Maybe Neil is waiting for patches to be submitted for changing these
> defaults, and to argue the merits in that context instead of pure
> discussion? Dunno. Just guessing. Maybe he'll read this and jump in.
>
Good guess.
NeilBrown
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prev parent reply other threads:[~2013-12-26 22:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <52B102FF.8040404@pzystorm.de>
[not found] ` <52B2FE9E.50307@hardwarefreak.com>
[not found] ` <52B41B67.9030308@pzystorm.de>
2013-12-20 22:43 ` XFS blocked task in xlog_cil_force_lsn Arkadiusz Miśkiewicz
2013-12-21 11:18 ` md-RAID5/6 stripe_cache_size default value vs performance vs memory footprint Stan Hoeppner
2013-12-21 12:20 ` Piergiorgio Sartor
2013-12-22 1:41 ` Stan Hoeppner
2013-12-26 8:55 ` Christoph Hellwig
2013-12-26 9:24 ` Stan Hoeppner
2013-12-26 22:14 ` NeilBrown [this message]
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