Date: Fri, 26 Jan 2007 15:36:48 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-current@freebsd.org Cc: Alexey Karagodov <karagodov@gmail.com>, Stefan Ehmann <shoesoft@gmx.net> Subject: Re: Interesting speed benchmarks Message-ID: <200701261536.48893.hselasky@c2i.net> In-Reply-To: <200701261341.03742.shoesoft@gmx.net> References: <20070125.192448.-432840241.imp@bsdimp.com> <cb5206420701260435s66e0687bnb467a42379d0a8d3@mail.gmail.com> <200701261341.03742.shoesoft@gmx.net>
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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@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 % --HPS * http://www.turbocat.net/~hselasky/usb4bsd or see the FreeBSD-perforce USB project.
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