> -----Original Message-----
> From: [email protected] [mailto:linux-raid-
> [email protected]] On Behalf Of Bill Davidsen
> Sent: Wednesday, September 28, 2005 4:05 PM
> To: Guy
> Cc: 'Holger Kiehl'; 'Mark Hahn'; 'linux-raid'; 'linux-kernel'
> Subject: Re: Where is the performance bottleneck?
>
> Guy wrote:
>
> >In most of your results, your CPU usage is very high. Once you get to
> about
> >90% usage, you really can't do much else, unless you can improve the CPU
> >usage.
> >
> That seems one of the problems with software RAID, the calculations are
> done in the CPU and not dedicated hardware. As you move to the top end
> drive hardware the CPU gets to be a limit. I don't remember off the top
> of my head how threaded this code is, and if more CPUs will help.
My old 500MHz P3 can xor at 1GB/sec. I don't think the RAID5 logic is the
issue! Also, I have not seen hardware that fast! Or even half as fast.
But I must admit, I have not seen a hardware RAID5 in a few years. :(
8regs : 918.000 MB/sec
32regs : 469.600 MB/sec
pIII_sse : 994.800 MB/sec
pII_mmx : 1102.400 MB/sec
p5_mmx : 1152.800 MB/sec
raid5: using function: pIII_sse (994.800 MB/sec)
Humm.. It did not select the fastest?
Guy
>
> I see you are using RAID-1 for your system stuff, did one of the tests
> use RAID-0 over all the drives? Mirroring or XOR redundancy help
> stability but hurt performance. Was the 270MB/s with RAID-0 or ???
>
> --
> bill davidsen <[email protected]>
> CTO TMR Associates, Inc
> Doing interesting things with small computers since 1979
>
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