Date: Mon, 22 Jun 2009 13:10:54 +0200 (CEST) From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> To: Sergey Babkin <babkin@verizon.net> Cc: =?ISO-8859-15?Q?Dag-Erling_Sm=F8rgrav?= <des@des.no>, freebsd-hackers@freebsd.org Subject: Re: is RTL8139 THAT bad? Message-ID: <alpine.BSF.2.00.0906221310140.28638@wojtek.tensor.gdynia.pl> In-Reply-To: <4A3EC37B.F589EA09@verizon.net> References: <alpine.BSF.2.00.0906211709420.1184@wojtek.tensor.gdynia.pl> <86eitdy4hl.fsf@ds4.des.no> <alpine.BSF.2.00.0906212219190.77226@wojtek.tensor.gdynia.pl> <4A3EC37B.F589EA09@verizon.net>
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>> >> But - this computer can do memcpy at 80MB/s, so at 3.5MB/s it should be 5% >> CPU for memcpy, and one interrupt per one packet (2500 packets/s). >> >> Is something more that make it consume >50% CPU? > > Accessing the on-card memory through PCI is guaranteed to be > slower than the main memory, and depending on the particular > card it may be much slower. as comment say - this card do DMA to main memory then computer must copy. so PCI speed needs just to be faster than 100Mbit/s, certainly is
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