From: hpa@zytor.com (H. Peter Anvin)
To: linux-kernel@vger.kernel.org
Subject: Re: AMD64 and RAID6
Date: Tue, 11 May 2004 02:13:47 +0000 (UTC) [thread overview]
Message-ID: <c7pcsr$u4e$1@terminus.zytor.com> (raw)
In-Reply-To: 409D1D86.6050907@clanhk.org
Followup to: <409D1D86.6050907@clanhk.org>
By author: "J. Ryan Earl" <heretic@clanhk.org>
In newsgroup: linux.dev.kernel
>
> I noticed the following in my dmesg:
>
> raid5: measuring checksumming speed
> generic_sse: 6604.000 MB/sec
> raid5: using function: generic_sse (6604.000 MB/sec)
> raid6: int64x1 1847 MB/s
> raid6: int64x2 2753 MB/s
> raid6: int64x4 2878 MB/s
> raid6: int64x8 1902 MB/s
> raid6: sse2x1 1015 MB/s
> raid6: sse2x2 1488 MB/s
> raid6: sse2x4 1867 MB/s
> raid6: using algorithm sse2x4 (1867 MB/s)
> md: raid6 personality registered as nr 8
> md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27
>
> Why doesn't RAID6 use the int64x4 algorithm in this situation? What is
> the motivation of setting the 'prefer field' on the sse algorithms and
> not on the integer based algorithms?
>
The SSE algorithms are non-cache-polluting. This makes them slightly
slower, but avoids slowing the rest of the machine down as much.
-hpa
prev parent reply other threads:[~2004-05-11 2:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-08 17:48 AMD64 and RAID6 J. Ryan Earl
2004-05-08 18:52 ` Jurriaan
2004-05-11 2:13 ` H. Peter Anvin [this message]
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