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Date:      Tue, 7 Apr 2009 12:57:48 +0800
From:      Sepherosa Ziehau <sepherosa@gmail.com>
To:        Ivan Voras <ivoras@freebsd.org>
Cc:        freebsd-net@freebsd.org
Subject:   Re: Advice on a multithreaded netisr patch?
Message-ID:  <ea7b9c170904062157u1c457f27md565f9a95a51a705@mail.gmail.com>
In-Reply-To: <grac1s$p56$1@ger.gmane.org>
References:  <gra7mq$ei8$1@ger.gmane.org> <alpine.BSF.2.00.0904051422280.12639@fledge.watson.org> <grac1s$p56$1@ger.gmane.org>

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On Sun, Apr 5, 2009 at 9:34 PM, Ivan Voras <ivoras@freebsd.org> wrote:
> Robert Watson wrote:
>>
>> On Sun, 5 Apr 2009, Ivan Voras wrote:
>>
>>> I thought this has something to deal with NIC moderation (em) but
>>> can't really explain it. The bad performance part (not the jump) is
>>> also visible over the loopback interface.
>>
>> FYI, if you want high performance, you really want a card supporting
>> multiple input queues -- igb, cxgb, mxge, etc.  if_em-only cards are

PCI-E em(4) supports 2 RX queues.  82571/82572 support 2 TX queues.
I have not tested multi-TX queues, but em(4) multi-RX queues work well
in dfly (tested with 82573 and 82571)

>> fundamentally less scalable in an SMP environment because they require
>> input or output to occur only from one CPU at a time.
>
> Makes sense, but on the other hand - I see people are routing at least
> 250,000 packets per seconds per direction with these cards, so they
> probably aren't the bottleneck (pro/1000 pt on pci-e).

It should be some variants of 82571EB

Best Regards,
sephe

-- 
Live Free or Die



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