Hi,
attached is a new version for fusb_linux.cc.
The current implementation uses three std::list lists for free, pending and
completed urbs, so submitting a single urb causes three allocs and three frees
(pushing and popping of the list).
The new implementation uses a circular list for the urbs, where each urb is
marked as free, pending or completed. As the total number of allocated urbs is
constant, no allocs or frees are needed.
Benchmark:
usrp/host/apps/test_usrp_standard_tx -B 512 -N 64 -M 128
old code needs ~990e6 instructions, new code 690e6 instructions. The call to
usrp_basic_tx::write goes down from 380e6 to 80e6 (so almost down to a fifth
...), the remaining instructions is the pattern fill for the sample buffer.
Regards,
Stefan
--
Stefan Brüns / Bergstraße 21 / 52062 Aachen
phone: +49 241 53809034 mobile: +49 151 50412019
/* -*- c++ -*- */
/*
* Copyright 2003 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include config.h
#endif
#include fusb_linux_2.h
#include usb.h // libusb header
#include stdexcept
#ifdef HAVE_LINUX_COMPILER_H
#include linux/compiler.h
#endif
#include linux/usbdevice_fs.h // interface to kernel portion of user mode usb driver
#include sys/ioctl.h
#include assert.h
#include string.h
#include algorithm
#include errno.h
#include string.h
#include iostream
#define MINIMIZE_TX_BUFFERING 1 // must be defined to 0 or 1
static const int MAX_BLOCK_SIZE = fusb_sysconfig::max_block_size(); // hard limit
static const int DEFAULT_BLOCK_SIZE = MAX_BLOCK_SIZE;
static const int DEFAULT_BUFFER_SIZE = 4 * (1L 20);// 4 MB / endpoint
enum urb_state_t { FREE, PENDING, COMPLETED };
struct _urb_private_data {
fusb_ephandle_linux* handle;
enum urb_state_t state;
// int count readers;
};
// Totally evil and fragile extraction of file descriptor from
// guts of libusb. They don't install usbi.h, which is what we'd need
// to do this nicely.
//
// FIXME if everything breaks someday in the future, look here...
static int
fd_from_usb_dev_handle (usb_dev_handle *udh)
{
return *((int *) udh);
}
inline static void
urb_set_ephandle (usbdevfs_urb *urb, fusb_ephandle_linux *handle)
{
((_urb_private_data*)(urb-usercontext))-handle = handle;
}
inline static fusb_ephandle_linux *
urb_get_ephandle (usbdevfs_urb *urb)
{
return ((_urb_private_data*)(urb-usercontext))-handle;
}
//
// USB request block (urb) allocation
//
static usbdevfs_urb *
alloc_urb (fusb_ephandle_linux *self, int buffer_length, int endpoint,
bool input_p, unsigned char *write_buffer)
{
usbdevfs_urb *urb = new usbdevfs_urb;
memset (urb, 0, sizeof (*urb));
urb-buffer_length = buffer_length;
// We allocate dedicated memory only for input buffers.
// For output buffers we reuse the same buffer (the kernel
// copies the data at submital time)
if (input_p)
urb-buffer = new unsigned char [buffer_length];
else
urb-buffer = write_buffer;
// init common values
urb-type = USBDEVFS_URB_TYPE_BULK;
urb-endpoint = (endpoint 0x7f) | (input_p ? 0x80 : 0);
// USBDEVFS_URB_QUEUE_BULK goes away in linux 2.5, but is needed if
// we are using a 2.4 usb-uhci host controller driver. This is
// unlikely since we're almost always going to be plugged into a
// high speed host controller (ehci)
#if 0 defined (USBDEVFS_URB_QUEUE_BULK)
urb-flags = USBDEVFS_URB_QUEUE_BULK;
#endif
urb-signr = 0;
urb-usercontext = new _urb_private_data;
((_urb_private_data*)urb-usercontext)-state=FREE;
urb_set_ephandle (urb, self);
return urb;
}
static void
free_urb (usbdevfs_urb *urb)
{
// if this was an input urb, free the buffer
if (urb-endpoint 0x80)
delete [] ((unsigned char *) urb-buffer);
delete (_urb_private_data*)(urb-usercontext);
delete urb;
}
//
// device handle
//
fusb_devhandle_linux::fusb_devhandle_linux (usb_dev_handle *udh)
: fusb_devhandle (udh)
{
// that's all
}
