Date: Mon, 11 Aug 2008 11:17:03 +0900 From: Pyun YongHyeon <pyunyh@gmail.com> To: Christian Weisgerber <naddy@mips.inka.de> Cc: freebsd-net@freebsd.org Subject: Re: Rx/tx hardware checksumming statistics? Message-ID: <20080811021703.GC50045@cdnetworks.co.kr> In-Reply-To: <g7ktnq$glp$1@lorvorc.mips.inka.de> References: <g7ktnq$glp$1@lorvorc.mips.inka.de>
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On Sat, Aug 09, 2008 at 08:12:42PM +0000, Christian Weisgerber wrote: > OpenBSD keeps count of the packets that have undergone IPv4 header/ > TCP/UDP checksumming in hardware. These statics are available with > netstat -s, e.g.: > > ip: > ... > 492152 input datagrams checksum-processed by hardware > 911338 output datagrams checksum-processed by hardware > ... > > This comes in quite handy to check whether checksum offloading > actually works and which protocols are successfully processed this > way. > I don't think it indicates whether checksum offloading actually works as OpenBSD blindly set a flag, which was derived from hardware, to indicate hardware performed the checksum computation. You can still have a chance that checksum offloading does not work even if the counter constantly increase over time. In addition, OpenBSD have a no way to disable checksum offloading feature of hardware on the fly so you have to rebuild the driver to disable checksum offloading in case of broken/buggy hardware. > On FreeBSD, netstat -s does not provide this information. Are these > statistics available in some other way? How would I check whether AFAIK there is no such counters in FreeBSD. > packets have actually been checksummed in hardware? > If checksum offloading didn't work you couldn't get a working connection at all. -- Regards, Pyun YongHyeon
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