From: Dave Chinner <david@fromorbit.com>
To: Stan Hoeppner <stan@hardwarefreak.com>
Cc: xfs@oss.sgi.com
Subject: Re: XFS: performance
Date: Tue, 30 Nov 2010 15:29:13 +1100 [thread overview]
Message-ID: <20101130042913.GB3556@dastard> (raw)
In-Reply-To: <4CF33D0F.6080404@hardwarefreak.com>
On Sun, Nov 28, 2010 at 11:41:35PM -0600, Stan Hoeppner wrote:
> Yclept Nemo put forth on 11/28/2010 9:57 PM:
> > You mention an eight-core machine (8c?). Since I operate a dual-core
> > system, would it make sense to increase my AG count slightly, to five
> > or six?
>
> Dave didn't mention the disk configuration of his "workstation". I'm
> guessing he's got a local RAID setup with 8-16 drives.
2 SSDs in RAID0.
> AG count has a
> direct relationship to the storage hardware, not the number of CPUs
> (cores) in the system.
Actually, I used 16 AGs because it's twice the number of CPU cores
and I want to make sure that CPU parallel workloads (e.g. make -j 8)
don't serialise on AG locks during allocation. IOWs, I laid it out
that way precisely because of the number of CPUs in the system...
And to point out the not-so-obvious, this is the _default layout_
that mkfs.xfs in the debian squeeze installer came up with. IOWs,
mkfs.xfs did exactly what I wanted without me having to tweak
_anything_.
> If you have a 24 core system (2x Magny Cours)
> and a single disk, creating an FS with 24 AGs will give you nothing, and
> may actually impede performance due to all the extra head seeking across
> those 24 AGs.
In that case, you are right. Single spindle SRDs go backwards in
performance pretty quickly once you go over 4 AGs...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2010-11-30 4:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-28 22:51 XFS: performance Yclept Nemo
2010-11-29 0:11 ` Dave Chinner
2010-11-29 1:21 ` Yclept Nemo
2010-11-29 1:59 ` Dave Chinner
[not found] ` <AANLkTikw086Z_66cz_U-EdFQx14TXP6XmiG-KyLN4BLo@mail.gmail.com>
2010-11-29 3:57 ` Yclept Nemo
2010-11-29 5:41 ` Stan Hoeppner
2010-11-30 4:29 ` Dave Chinner [this message]
2010-11-30 4:50 ` Stan Hoeppner
2010-11-30 7:51 ` Dave Chinner
2010-12-01 0:47 ` Stan Hoeppner
2010-11-29 8:38 ` Michael Monnerie
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