Date: Tue, 24 Nov 2009 11:40:25 -0800 From: Pyun YongHyeon <pyunyh@gmail.com> To: "Yuriy A. Korobko" <administrator@shtorm.com> Cc: freebsd-net@freebsd.org Subject: Re: Reducing number of interrupts from intel pro 1000 et adapter Message-ID: <20091124194025.GA1116@michelle.cdnetworks.com> In-Reply-To: <1258998140.3015.34.camel@stormi-desktop> References: <1258998140.3015.34.camel@stormi-desktop>
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On Mon, Nov 23, 2009 at 07:42:20PM +0200, Yuriy A. Korobko wrote: > Hi, > > I'd like to know a way to control tx interrupts on intel pro 1000 et > adapter with igb driver. Just installed one in the router and systat > shows 8-9k rx interrupts and 20k tx interrupts from igb0 and igb1 > adapters. Box is a router running freebsd 7.2 release, I've tried > default driver from kernel source and latest from intel site, effect is > the same with automatic interrupt moderation enabled and disabled. I I'm also aware of this issue. Here is patch I'm currently experimenting. It seems igb(4) wants to dynamically adjust interrupt moderation on Rx traffic such that this seems to cause lots of Tx interrupts under heavy Rx traffic. I simply disabled that feature and fixed Rx handler not to generate more interrupts. Without Rx handler fix the igb(4) took all CPU cycles under heady load(64 bytes UDP torture test) I couldn't even type a character on console. You can get my patch at the following URL. http://people.freebsd.org/~yongari/igb/igb.buf.patch5 The patch also includes other changes I made so it's somewhat big. Note, please don't apply the patch on production servers it needs more testing. > have the same box with intel pro 1000 pt adapter which have > tx(rx)_int_delay sysctls in em driver, I was able to reduce number of > tx/rx interrupts to 7-8k per interface and got much more cpu idle > because of less context switches with same pps. > I guess you sacrificed latencies.
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