Re: [Libusb-devel] Slow USB bulk transfer

[Dan E. <Dan...@di...>]

You'll do much better if you write more than 512 bytes at a time, e.g.
64kB. At the moment you're waiting for each 512 bytes to be transmitted
before the next one is sent. This is going to take at least 125us per
call, and probably quite a bit longer (e.g. 500us).
=20
Dan.

________________________________

From: lib...@li...
[mailto:lib...@li...] On Behalf Of
mohammed abuhijle
Sent: 28 February 2007 14:19
To: lib...@li...
Subject: [Libusb-devel] Slow USB bulk transfer


Hello,

I have the following code that takes more than a min to finisg:

-------------------------------------------------------
#include <stdio.h>
#include <string.h>
#include <usb.h>=20

// Search token for the cypress chip.
#define CYP_VENDOR_ID   0x04b4
#define CYP_PRODUCT_ID 0x8613

struct usb_device* cypress_init();
void sighandler(int );

=20
// Global vars
struct usb_device* cypress_dev;=20
struct usb_dev_handle* cypress_dev_handle;=20
char* bytes;
struct usb_interface_descriptor interface ;

int verbose =3D 0;
int c,i,a,ret;

int main(int argc, char* argv[]){
// First, init the cypress chip..=20
cypress_dev =3D cypress_init();=20
// Second, open it ...
if (cypress_dev) cypress_dev_handle =3D usb_open(cypress_dev);
else {
    printf("Fatel Error: No Cypress CY7C68xx devices connected. Exiting
\n");=20
    return -9;
}

if (cypress_dev_handle){
// Now, detatch the usbtest kernel driver assigned to the cypress chip
upon=20
//hotpluging it into the system
usb_detach_kernel_driver_np(cypress_dev_handle ,0);=20

usb_set_configuration(cypress_dev_handle,
cypress_dev->config->bConfigurationValue);
interface =3D cypress_dev->config[0].interface[0].altsetting[1];

usb_claim_interface(cypress_dev_handle,interface.bInterfaceNumber );
usb_set_altinterface(cypress_dev_handle,interface.bAlternateSetting);

//assign the endpoint addresses....
int epo   =3D interface.endpoint[0].bEndpointAddress;
int epi   =3D interface.endpoint[1].bEndpointAddress;=20

usb_clear_halt(cypress_dev_handle, epi );

//printf ("ep_out is %0x while ep_in is %0x\n",epo,epi);
bytes =3D (char*) malloc(512);
memset(bytes,0,sizeof(bytes));

/*write 40 Mbytes worth of data to the bulk endpoint*/=20
/*i am calculating this by: 512 (packet size) * 2 =3D 1 KB, * 1000 =3D =
1MB,
* 40 =3D 40 MB*/
for (i =3D 0; i < 2 * 1000 * 40 ; i++){
ret =3D usb_bulk_write(cypress_dev_handle, epi,bytes, 512, 0 /*the =
timrout
is ignored for bulk transfer*/);=20
//printf ("i is:%d\t ret is %d\t bytes is %s\n",i, ret,bytes);
}

}
else {
    printf("Could not open the Cypress chip. Quiting \n");
    return -1;
    }

usb_release_interface(cypress_dev_handle,0);=20
usb_close(cypress_dev_handle);

return 0;=20
}   =20

struct usb_device* cypress_init(){
   =20
struct usb_bus *bus =3DNULL;=20
struct usb_device *dev =3DNULL;   =20

usb_init();=20
usb_find_busses();=20
usb_find_devices();
usb_set_debug(9);

for (bus =3D usb_busses; bus;  bus =3D bus->next)=20
   for (dev =3D bus->devices; dev;  dev =3D dev->next)=20
       if ((dev->descriptor.idVendor =3D=3D  CYP_VENDOR_ID)    &&=20
             (dev->descriptor.idProduct =3D=3D  CYP_PRODUCT_ID)) return =
dev;

  =20
return NULL;
}

void sighandler(int sig){
   =20
//usb_release_interface(cypress_dev_handle,0);
usb_close(cypress_dev_handle);   =20
   =20
}

-------------------------------------------------------

As root, I ran "time ./a.out" and got

# time ./a.out
real    1m9.793s
user    0m0.118s
sys     0m0.490s

# time ./a.out

real    1m15.078s
user    0m0.095s
sys     0m0.438s
root@elive[/home/me/cypress]#


The lsusb -vv output of the cypress FX2 device is at:=20

http://abuhijle.googlepages.com/libusb-vvoutput

I am trying to achieve that max possible speed to write to the device.
There are no other processes I am running along with a.out. My goal is
to reduce this > 1 minute to less than one second!! It is a USB 2, I
know I should not expect the standard's  60 MBytes  transfer rate
because of overhead and all other issues so I am shooting for 40.=20


Any errors in my code, please..? Any tipe on making this faster....

here are some more info:=20

# libusb-config --version
0.1.12

# uname -a
Linux elive 2.6.15.7 #2 Tue Dec 5 06:48:06 CET 2006 i686 GNU/Linux

gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v
--enable-languages=3Dc,c++,fortran,objc,obj-c++,treelang --prefix=3D/usr
--enable-shared --with-system-zlib --libexecdir=3D/usr/lib
--without-included-gettext --enable-threads=3Dposix --enable-nls
--program-suffix=3D- 4.1 --enable-__cxa_atexit --enable-clocale=3Dgnu
--enable-libstdcxx-debug --enable-mpfr --with-tune=3Di686
--enable-checking=3Drelease i486-linux-gnu
Thread model: posix
gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21 )











-M