Wrong checksumming function chosen

Wrong checksumming function chosen

[Sebastian Schäfer]

Hi!

It seems as my computer (Athlon XP 2000+) chooses the wrong checksumming
function.

The kernel output is as follows:

raid5: measuring checksumming speed
   8regs     :  2564.000 MB/sec
   32regs    :  2260.000 MB/sec
   pIII_sse  :  4748.400 MB/sec
   pII_mmx   :  3921.200 MB/sec
   p5_mmx    :  5022.400 MB/sec
raid5: using function: pIII_sse (4748.400 MB/sec)

I hope I can help the developers with this piece of information.
And I also hope I mailed at the right address.

Greets,
-- 
Sebastian Schäfer
E-Mail: sarek@uliweb.de || http://www.uliweb.de
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Re: Wrong checksumming function chosen

[Neil Brown]

On Sunday September 22, sarek@uliweb.de wrote:
> Hi!
> 
> It seems as my computer (Athlon XP 2000+) chooses the wrong checksumming
> function.
> 
> The kernel output is as follows:
> 
> raid5: measuring checksumming speed
>    8regs     :  2564.000 MB/sec
>    32regs    :  2260.000 MB/sec
>    pIII_sse  :  4748.400 MB/sec
>    pII_mmx   :  3921.200 MB/sec
>    p5_mmx    :  5022.400 MB/sec
> raid5: using function: pIII_sse (4748.400 MB/sec)
> 
> I hope I can help the developers with this piece of information.
> And I also hope I mailed at the right address.

The only problem here is that the message is misleading.

pIII_sse is deliberately chosen despite appearing not to be so fast
because it avoid the level-1 cache which is appropriate for this data
which is only used by the CPU once.

NeilBrown


> 
> Greets,
> -- 
> Sebastian Schäfer
> E-Mail: sarek@uliweb.de || http://www.uliweb.de
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
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