Date: Thu, 29 Jan 2004 20:33:48 +0100 From: Philip Nienhuis <[EMAIL PROTECTED]> Subject: Re: [LIB] Networking problems
Raymond wrote: > >From: "Matt Hanson" <[EMAIL PROTECTED]> > >Subject: Re: [LIB] Networking problems <snip> > >Also, since I tested xfer rates both between Libbys and beteen each of > >them and the desktop with the same results, I guess components are not the > >problem. I guess it's just a limitation of the CPU, and what supports and > >augments it. > > Hi Matt, > > There is a logical explanation for all this and I'm almost certain the > problem here is CPU power. There is a big difference between dumping > digital videos through firewire at almost 30Mbps and only managing 5Mbps > through a network card. Firstly, firewire cards (and, to a lesser extent, > USB2.0 devices) have onboard controllers. In my card (and I assume almost > all firewire cards), the firewire stream goes straight to system memory via > the DMA (direct memory access, allows devices to read/write to/from main > memory independant of the system processor) controller, bypassing the CPU > altogether. All the CPU has to do is grab the data out of memory and shove > it out to disk (the video is uncompressed and, as far as I'm aware, comes > across the firewire cable in a format that is almost like uncompressed AVI > anyway). In fact, if the video is already interleaved correctly, all the > CPU needs to do is monitor the DMA controller until it says it has a block > of data then tell the IDE controller (also on DMA) to grab data from that Are you sure about DMA in the Libretto? AFAIK the Libretto 30-110 IDE (which is attached tru a plain vanilla ISA bus) simply has no DMA support. PIO mode 4 is the best I could ever get on my Lib110 in Win2K, OS/2 and Linux. <snip> : > In contrast, a network card presents the CPU with network packets which > must be processed, error checked, resent if corrupted and so-on as > specified by the various protocols involved (TCP/IP and SMB if you're using > Windows filesharing over IP for instance). The CPU needs to do a lot of > work before it can unwrap the data encapsulated in a network transmission > and I can well believe that the poor L70 or even the L110 will croak once > you get around the 6Mbps mark. NIC brands do make a big difference, as some take 60-80 % CPU time, especially in 100Mbps mode, while other brands do a lot by themselves and leave more CPU time for other processes. Cheap NIC cards rarely perform as well as e.g. 3Com, Xircom, .... It is really a matter of value for money here. Just for reference, I checked the transfer speed here with 3 LAN PC-Cards: (Lib110 <-> 1.6+ Ghz AthlonXP all Win2K), copying 79 MB with plain NETBEUI/Netbios (not over TCP/IP, as that is 5-10 % slower due to TCP overhead): - Xircom CEM33 (10 Mbps / full duplex): 2 min 18 sec - Conceptronic CON100TCL (100 Mbps / full duplex): 0 min 47 sec - IBM 10/100 Etherjet (100 Mbps / full duplex): 1 min 02 sec (oh and yes, I got a switch in between), so the fastest effective rate I got is in the order of 1.4 MByte/second. I'm afraid that's as fast as one can get on a L110, probably slower on a L100 (lower CPU speed), not to mention L70. BTW It's remarkable that the 32bit Cardbus IBM Etherjet (actually rebranded Xircom) is actually slower than the 16bit Conceptronic. Philip ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://www.silverace.com/libretto/ - Archives -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
