Date: Tue, 4 Sep 2012 12:13:10 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hardware@freebsd.org Cc: Andy Young <ayoung@mosaicarchive.com> Subject: Re: What is rx_processing_limit sysctl for Intel igb NIC driver? Message-ID: <201209041213.10931.jhb@freebsd.org> In-Reply-To: <CAHMRaQeQGfwx4yLP6_nZWVePHoKeGgW6bOh9MSUoN20Hg%2B7iOw@mail.gmail.com> References: <CAHMRaQeQGfwx4yLP6_nZWVePHoKeGgW6bOh9MSUoN20Hg%2B7iOw@mail.gmail.com>
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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
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