Date: Thu, 6 Sep 2012 17:45:21 +0300 From: Nikolay Denev <ndenev@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: Andy Young <ayoung@mosaicarchive.com>, freebsd-hardware@freebsd.org Subject: Re: What is rx_processing_limit sysctl for Intel igb NIC driver? Message-ID: <8876AEF9-0D0E-42A1-9B83-F2F7D36D7B7F@gmail.com> In-Reply-To: <201209041213.10931.jhb@freebsd.org> References: <CAHMRaQeQGfwx4yLP6_nZWVePHoKeGgW6bOh9MSUoN20Hg%2B7iOw@mail.gmail.com> <201209041213.10931.jhb@freebsd.org>
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On Sep 4, 2012, at 7:13 PM, John Baldwin <jhb@freebsd.org> wrote: > On Sunday, September 02, 2012 10:41:15 pm Andy Young wrote: >> I am tuning our server that has an Intel 82576 gigabit NIC using the igb >> driver. I see a lot of posts on the net where people bump the >> rx_processing_limit sysctl from the default value of 100 to 4096. Can >> anyone tell me what this is intended to do? > > If you have multiple devices sharing an IRQ with igb (and thus are not using > MSI or MSI-X), it forces the driver to more-or-less cooperatively schedule > with the other interrupts on the same IRQ. However, since igb uses a fast > interrupt handler and a task on a dedicated taskqueue in the non-MSI case now, > I think it doesn't even do that. It should probably be set to -1 (meaning > unlimited) in just about all cases now. > > -- > John Baldwin > _______________________________________________ > freebsd-hardware@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hardware > To unsubscribe, send any mail to "freebsd-hardware-unsubscribe@freebsd.org" And setting it to -1 gave a nice performance improvement in some tests that I did recently. AFAIR only after setting this to -1 I was able to reach 10gig speed using iperf on two directly connected machines with ix(4) 82599help
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