Strange USB performance issue

tutaepaki · Posted: Wed May 03, 2006 8:48 pm Post subject: Strange USB performance issue

I recently installed a PCI USB2.0 card in my desktop. Mainly to try to improve the performance when putting musinc on my iPod shuffle. But it seems MUCH slower.

But not just when writing to the iPod. When the USB2 card is installed, they whole machine seems slower. It's particularly noticable with GTKPOD. It doesn't seem to matter whether I plug the iPod into the old USB1.1 ports on the Motherboard or into the new ports, when I start GTKPOD, it takes ~45secs to read the 75 tracks off the iPod, whereas, when I physically remove the new card, it takes 3-4secs. I see the same effect when I select the LOCAL music database, and the iPod is not even connected. ~100tracks per minute with the card in, ~100tracks every 5-6secs with it out. (while this is happening, GTKPOD is using 80-90% CPU)

The machine is a P3 650 with 512MB RAM Kernel 2.6.16-r2

USB DMESG output is

E001754 · Posted: Wed May 03, 2006 10:38 pm Post subject:

perhaps trying to activate DMA using hdparm ?? (kick my ass if DMA is not available on SCSI-like chains. I don't remember for sure, but it should).

tutaepaki · Posted: Wed May 03, 2006 11:59 pm Post subject:

DMA doesn't seem to be supported "HDIO_SET_DMA failed: Invalid argument"

thanks anyway

E001754 · Posted: Thu May 04, 2006 8:17 pm Post subject:

Have you tested the performances with a standard USB 2.0 stick ??
It could help to findout whereever you should accuse your Ipod or your computer.

tutaepaki · Posted: Thu May 04, 2006 8:57 pm Post subject:

haven't tried that yet...will do tonight....but some more speed tests with the iPod...

without the USB 2.0 card (so using the built-in USB 1.1 port)
hdparm gives me speeds of 954kB/sec which seems pretty reasonable (~8Mb/sec and 1.1 has a max of 12Mb/sec so that seems OK
gtkpod takes ~1sec to load the list of tracks off the iPod

with the USB 2.0 card in
hdparm gives the same speed for the 1.1 port
and 3MB/sec for the 2.0 one (at ~24Mb/sec that's higher than the cabability of 1.1, but well short of 2.0's limit of 48Mb/sec)
gtkpod takes ~30-45secs to load the list of tracks off the iPod no matter which USB port it's connected in to

I also get the general impression that everything is slower with the 2.0 card installed. I did an emerge system last night on a couple of systems, and glibc took just as long on the 650Mhz with 512MB RAM as it did on the 350Mhz with 128MB. If I can recall the command to display the timings I'll confirm that.

So, I'm thinking maybe it's not necessarily the USB speed, but that the card itself is doing something to my processor. Maybe a BIOS upgrade needed or something?

EDIT : Erk

E001754 · Posted: Fri May 05, 2006 7:48 pm Post subject:

I was thinking about something (yes, really !

)

With your USB 2.0 card inside your PC, you now have two USB controlers.
If I were you, I would try disabling the on-board USB, so that you are sure the USB 1.1 on-board controler can't mess up with the PCI USB 2.0 controler.

Perhaps is there some weird interactions outta there ?

Give it a try and let me know the result.

chrisruwe · Apprentice Joined: 17 Apr 2006 Posts: 160

I noticed your actual speed is pretty close to 1/2 of the theoretical one. Could this bear any significance? Maybe some jumper-setting or some bandwidth sharing with another device?