Date: Thu, 03 Jul 2008 14:57:09 +0200 From: Kris Kennaway <kris@FreeBSD.org> To: Zbigniew Szalbot <z.szalbot@lc-words.com> Cc: User Questions <freebsd-questions@freebsd.org> Subject: Re: 7.0-release / systat / 3GB Message-ID: <486CCCA5.4030807@FreeBSD.org> In-Reply-To: <486CAB51.4070207@lc-words.com> References: <486BA8C1.90107@lc-words.com> <20080702200904.T2523@wojtek.tensor.gdynia.pl> <486C7BE3.4070208@FreeBSD.org> <486CAB51.4070207@lc-words.com>
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Zbigniew Szalbot wrote: > Hello, > > Kris Kennaway: >> Wojciech Puchar wrote: >>>> I am a bit curious though why once the outgoing bandwidth exceeds >>>> (more or less) 3GB, the Total counter gets reset and starts counting >>>> from scratch. >>> isn't it 4GB - because of 32-bit unsigned counter? >> >> I would guess so. >> >> Using a 64-bit counter on 32-bit systems would cause additional >> processing overhead for little benefit. > > I have confirmed (with assistance from Wojtek Puchar) that the problem > of resetting a Total counter for 'systat -ifstat' happens every 4GB (not > 3GB) amount of data. It only affects i386 machines. amd64 machines are > not affected. > > I have tested this on 7.0 and 6.1-Release versions. Here's an example > > em0 in 104.564 KB/s 104.564 KB/s 2.401 GB > out 220.282 KB/s 284.090 KB/s 3.874 GB > > em0 in 17.416 KB/s 220.306 KB/s 2.404 GB > out 257.781 KB/s 284.090 KB/s 3.902 GB > > em0 in 35.181 KB/s 803.832 KB/s 2.420 GB > out 170.575 KB/s 284.090 KB/s 3.980 GB > > em0 in 11.020 KB/s 803.832 KB/s 2.423 GB > out 27.773 KB/s 284.090 KB/s 3.998 GB > > em0 in 5.515 KB/s 803.832 KB/s 2.423 GB > out 97.953 KB/s 284.090 KB/s 4.000 GB > > em0 in 7.944 KB/s 803.832 KB/s 2.423 GB > out 71.475 KB/s 284.090 KB/s 25.019 KB > > I have submitted a pr in case this can be fixed. > > http://www.freebsd.org/cgi/query-pr.cgi?pr=125196 I explained above why it cannot reasonably be fixed on i386 :-) Kris
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