Message-ID: <45360952.5020307@aitel.hist.no>
Date: Wed, 18 Oct 2006 13:00:34 +0200
From: Helge Hafting <helge.hafting@aitel.hist.no>
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To: Jens Axboe <jens.axboe@oracle.com>
CC: Jakob Oestergaard <jakob@unthought.net>,
       Arjan van de Ven <arjan@infradead.org>,
       "Phetteplace, Thad (GE Healthcare, consultant)" 
	<Thad.Phetteplace@ge.com>,
       linux-kernel@vger.kernel.org
Subject: Re: Bandwidth Allocations under CFQ I/O Scheduler
References: <CAEAF2308EEED149B26C2C164DFB20F4E7EAFE@ALPMLVEM06.e2k.ad.ge.com> <1161048269.3245.26.camel@laptopd505.fenrus.org> <20061017132312.GD7854@kernel.dk> <20061018080030.GU23492@unthought.net> <20061018095125.GE24452@kernel.dk>
In-Reply-To: <20061018095125.GE24452@kernel.dk>
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Jens Axboe wrote:
> While that may make some sense internally, the exported interface would
> never be workable like that. It needs to be simple, "give me foo kb/sec
> with max latency bar for this file", with an access pattern or assumed
> sequential io.
>
> Nobody speaks of iops/sec except some silly benchmark programs. I know
> that you are describing pseudo-iops, but it still doesn't make it more
> clear.
> Things aren't as simple
>   
How about "give me 10% of total io capacity?"  People understand
this, and the io scheduler can then guarantee this by ensuring
that the process gets 1 out of 10 io requests as long as it
keeps submitting enough.

The admin can then set a reasonable percentage depending on
the machine's capacity.

Helge Hafting
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