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linux-next/arch/um/drivers/ubd_user.c
Anton Ivanov f88f0bdfc3 um: UBD Improvements
UBD at present is extremely slow because it handles only
one request at a time in the IO thread and IRQ handler.

The single request at a time is replaced by handling multiple
requests as well as necessary workarounds for short reads/writes.

Resulting performance improvement in disk IO - 30%

Signed-off-by: Anton Ivanov <aivanov@kot-begemot.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
2016-12-14 22:46:55 +01:00

79 lines
1.5 KiB
C

/*
* Copyright (C) 2016 Anton Ivanov (aivanov@brocade.com)
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Copyright (C) 2001 Ridgerun,Inc (glonnon@ridgerun.com)
* Licensed under the GPL
*/
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <string.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <endian.h>
#include <byteswap.h>
#include "ubd.h"
#include <os.h>
#include <poll.h>
struct pollfd kernel_pollfd;
int start_io_thread(unsigned long sp, int *fd_out)
{
int pid, fds[2], err;
err = os_pipe(fds, 1, 1);
if(err < 0){
printk("start_io_thread - os_pipe failed, err = %d\n", -err);
goto out;
}
kernel_fd = fds[0];
kernel_pollfd.fd = kernel_fd;
kernel_pollfd.events = POLLIN;
*fd_out = fds[1];
err = os_set_fd_block(*fd_out, 0);
err = os_set_fd_block(kernel_fd, 0);
if (err) {
printk("start_io_thread - failed to set nonblocking I/O.\n");
goto out_close;
}
pid = clone(io_thread, (void *) sp, CLONE_FILES | CLONE_VM, NULL);
if(pid < 0){
err = -errno;
printk("start_io_thread - clone failed : errno = %d\n", errno);
goto out_close;
}
return(pid);
out_close:
os_close_file(fds[0]);
os_close_file(fds[1]);
kernel_fd = -1;
*fd_out = -1;
out:
return err;
}
int ubd_read_poll(int timeout)
{
kernel_pollfd.events = POLLIN;
return poll(&kernel_pollfd, 1, timeout);
}
int ubd_write_poll(int timeout)
{
kernel_pollfd.events = POLLOUT;
return poll(&kernel_pollfd, 1, timeout);
}