netdev - Re: 32 core net-next stack/netfilter "scaling"

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Hash Suite: Windows password security audit tool. GUI, reports in PDF.

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Date:	Tue, 27 Jan 2009 23:34:02 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Rick Jones <rick.jones2@...com>
CC:	Netfilter Developers <netfilter-devel@...r.kernel.org>,
	Patrick McHardy <kaber@...sh.net>,
	Linux Network Development list <netdev@...r.kernel.org>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: Re: 32 core net-next stack/netfilter "scaling"

Rick Jones a écrit :
>
>> Thanks for the report
>>
>> If you have so much contention on spinlocks, maybe hash function is 
>> not good at all...
>>
>> hash = (unsigned long)ct;
>> hash ^= hash >> 16;
>> hash ^= hash >> 8;
>>
>> I ass-u-me you compiled your kernel with NR_CPUS=32 ?
>
> I believe so - CONFIG_NR_CPUS in .config is 64 anyway.  If there is a 
> more definitive place to check I'd be happy to look.
>
> rick
>
>

By any chance, are you using SLAB instead of SLUB ?

While running your netperf session, issuing :

grep conntrack /proc/slabinfo

Would help to know hash dispertion on your machine.


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