Date: Fri, 30 Jan 2004 09:32:18 +0800 From: Raymond <[EMAIL PROTECTED]> Subject: Re: [LIB] Networking problems
> 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.
You might be right there ... although the Libretto's IDE controller IS on the PCI bus (well OK it's on the "Extended IO Bus" which hangs off the PCI bus, which I don't think is the legacy ISA bus because it has the DMA controller and what I'm pretty sure is the DMA-enabled Cardbus slots hanging off it), I too can't get the hard drives to snap out of PIO mode (although it is in "DMA if available" mode) ... I might do some more poking around later though ...
<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.
True too ...
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.
I dunno about the Libretto but I've had remarkable differences in CPU usage with different drivers on a PC I used to have with an Intel Pro 100/B network adapter ... *sigh* that's the problem with computers ... soooo many different factors ... heh
- Raymond
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