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Re: The XFS real-time subvolume in Linux

To: Andi Kleen <ak@xxxxxxx>
Subject: Re: The XFS real-time subvolume in Linux
From: Eric Sandeen <sandeen@xxxxxxx>
Date: Tue, 04 Oct 2005 10:39:46 -0500
Cc: linux-xfs@xxxxxxxxxxx, dmarkic@xxxxxxxxxxx
In-reply-to: <p73u0fxz4xa.fsf@verdi.suse.de>
References: <BAY110-F272BEC2E5C429160FB4068B4830@phx.gbl> <434298D3.4060501@sgi.com> <p73u0fxz4xa.fsf@verdi.suse.de>
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Andi Kleen wrote:
Eric Sandeen <sandeen@xxxxxxx> writes:

That is basically true, yes.  There is a non-free GRIOV2 product in
use with CXFS, but for your purposes, I think it is safe to say that
there is no standalone GRIO equivalent on Linux.

It's not. In fact it's a standard feature now.

Well, I stand corrected then :)

The CFQ2 IO scheduler has IO priorities settable with ionice, including
a RT class with 8 priorities.

Well, that still sounds a bit different from the original irix GRIO implemenation, FWIW.

     grio - guaranteed-rate I/O


     Guaranteed-rate I/O (GRIO) refers to a guarantee made by the system to a
     user process indicating that the given process will receive data from a
     system resource at a predefined rate regardless of any other activity on
     the system.

While 2.6 can set priorities on IO, it does not offer a hard guaranteed IO rate, does it? Now, I'm not necessarily saying one scheme is necessarily better or worse than the other, but they are different, I think.


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