Re: Interesting speed benchmarks

Hans Petter Selasky wrote:
> On Friday 26 January 2007 13:41, Stefan Ehmann wrote:
>> On Friday 26 January 2007 13:35, Andrew Pantyukhin wrote:
>>> On 1/26/07, Stefan Ehmann <shoesoft_at_gmx.net> wrote:
>>>> On Friday 26 January 2007 11:00, Alexey Karagodov wrote:
>>>>> what manufacturer says about usb speeds?
>>>>> that is the question
>>>> Well, "up to 56MB/s" which is pretty much full USB2 speed.
> 
> It is called high speed USB, and it can go up 53 MB/s with a payload of 512 
> bytes per packet according to "Table 5-10. High-speed Bulk Transaction 
> Limits" in the USB 2.0 specification. The table does not say anything about 
> whether this include bit-stuffing or not. If bit stuffing is not included, 
> then you have to divide this value by 1.20 approximately for the worst case, 
> all 1's. 53 MB/s div 1.20 = 44 MB/s.
> 
>>>> But writing it on the box doesn't mean the speed can actually be
>>>> reached.
>>>>
>>>> Benchmarking on windows might be interesting, but I don't know how to
>>>> measure raw disk io on windows.
>>> Format the disk, copy a large file to/from it, divide
>>> its size by time spent, add the word "approximately" :-)
>> I'd rather not format a drive with my backups and other stuff on it :-)
> 
> Results with the new USB stack*:
> 
> Changing the interrupt delay from 2 microframes to 1 microframe gave me 
> 2MBytes more per second on the EHCI controller.
> 
> I connected two high speed "umass" capable devices to the same EHCI controller 
> on my computer, and did a "dd" on both devices at the same time, with a block 
> size of 131072 bytes.
> 
> The one device transferred 22 MB/s. The other device transferred 16 MB/s. 
> Summed up this yields 38 MB/s. Used alone these devices can transfer 27 MB/s 
> and 20 MB/s. It seems clear that the EHCI controller is saturated at 38 MB/s. 
> 
> %dmesg |grep ehci
> ehci0: <Intel 82801DB/L/M (ICH4) USB 2.0 controller> mem 0xe0100000-0xe01003ff 
> irq 10 at device 29.7 on pci0
> usb3: <Intel 82801DB/L/M (ICH4) USB 2.0 controller> on ehci0
> %
> 

Just FYI.

I get about the same performance on my laptop running Windows XP when
moving between local 100 mb 5400 rpm ATA and 250 mb 7200 rpm USB2.0 disk.
I have the same controller.

-- 
Sten Daniel Sørsdal