Messages in this thread | | | Date | Thu, 20 Mar 2008 01:31:30 +0100 | From | Rene Herman <> | Subject | Re: ehci-hcd affects hda speed |
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On 20-03-08 00:47, Lev A. Melnikovsky wrote:
> Just in case - I do have an A7V8X-based PC in the office and have > performed a simple experiment. > > #1. Idle USB controller has no effect on PCI performance (I again > measured hda throughput). > > #2. Default value for register 4Bh is 09h. > > #3. I have detected no effect of changing [4Bh]=29h. Particularly, USB > FLASH read speed is ~8MB/s and hda read speed is ~40MB/s regardless of > [4Bh] content. During hda timing, "dd if=/dev/sda of=/dev/null bs=1024" > was running in another window (/dev/sda being the USB stick). > > My interpretation, is that bit5 at offset 4B may _not_ be an "EHCI sleep > time select" like it is for VT6212. Am I missing something?
No, very useful test, thanks much. Patch as submitted for revision 0x6x will stand then.
I do wonder -- is your hda throughput also the same before _ever_ attaching anything to the EHCI controller and after? In my case, the slow down only happened after switching on my external USB drive once, and would persist from that time until reboot (or unloading ehci-hcd, which I kept modular for exactly that reason).
The sleep time wasn't the core problem, so I wonder of later VIA chips do still have the active async schedule problem...
Alessandro? You said there still was a difference for you between no EHCI at all and EHCI after tweaking 4B as Lev showed. How much?
Rene.
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