Date: Thu, 17 Jan 2002 17:44:48 +0100 (CET) From: Michal Mertl <mime@traveller.cz> To: arch@freebsd.org Subject: Re: 64 bit counters again Message-ID: <Pine.BSF.4.41.0201171742520.5459-100000@prg.traveller.cz>
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I promise that if there isn't anything new from you this is the last time I'm talking about it. I wan't to inform you that I tried to look at some system pushing data with different size/implementation network counters. I did my last test on dual PIII 750. I don't know, of any good way to measure the load, so I just run vmstat -w1 (and calculated average idle) while pushing the data and also looked at the throughput at 100Mbit Full-Duplex. System was performing about 10000 interrupts and 15000 packets per second. I didn't notice any difference between using 32 bits non atomic operations (3 clocks per op) or 64 bit atomic (lock;cmpxchg8b - 50 clocks). I did also measure it on single Duron 800 with the same result. It was TCP traffic so there were at least three classes of counters updated - interface, ip and tcp. Interface counters were rather cheap because fxp does updating only once per second but protocol were I think worse. Just a dumb guess is that there were 5 adds per packet so it means losing 15000*47*5=3525000 clocks. Judge by yourself. -- Michal Mertl mime@traveller.cz To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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