Attachment 275191 Details for Bug 408131 – eliminate 1 ms wakeups

[patch] eliminate 1 ms wakeups

libusb-no-wakeups.patch (text/plain), 1.75 KB, created by Scott Lamb on 2007-12-03 01:48:55 UTC

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Creator: Scott Lamb

Created: 2007-12-03 01:48:55 UTC

Size: 1.75 KB

patch

obsolete

>Remove unnecessary 1ms wakeups while USB transfers are in progress
>
>--- linux.c.orig	2007-12-02 16:02:27.000000000 -0800
>+++ linux.c	2007-12-02 16:33:12.000000000 -0800
>@@ -14,6 +14,7 @@
> #include <errno.h>
> #include <sys/time.h>
> #include <dirent.h>
>+#include <poll.h>
> 
> #include "linux.h"
> #include "usbi.h"
>@@ -164,7 +165,7 @@
> {
>   struct usb_urb urb;
>   int bytesdone = 0, requested;
>-  struct timeval tv, tv_ref, tv_now;
>+  struct timeval tv_ref, tv_now;
>   struct usb_urb *context;
>   int ret, waiting;
> 
>@@ -191,8 +192,6 @@
>   }
> 
>   do {
>-    fd_set writefds;
>-
>     requested = size - bytesdone;
>     if (requested > MAX_READ_WRITE)
>       requested = MAX_READ_WRITE;
>@@ -213,25 +212,25 @@
>       return ret;
>     }
> 
>-    FD_ZERO(&writefds);
>-    FD_SET(dev->fd, &writefds);
>-
> restart:
>     waiting = 1;
>     context = NULL;
>     while (!urb.usercontext && ((ret = ioctl(dev->fd, IOCTL_USB_REAPURBNDELAY, &context)) == -1) && waiting) {
>-      tv.tv_sec = 0;
>-      tv.tv_usec = 1000; // 1 msec
>-      select(dev->fd + 1, NULL, &writefds, NULL, &tv); //sub second wait
>+      struct pollfd pollfd;
>+      int poll_timeout = -1;
>+
>+      pollfd.fd = dev->fd;
>+      pollfd.events = POLLOUT;
>+      pollfd.revents = 0;
> 
>       if (timeout) {
>-        /* compare with actual time, as the select timeout is not that precise */
>         gettimeofday(&tv_now, NULL);
>-
>-        if ((tv_now.tv_sec > tv_ref.tv_sec) ||
>-            ((tv_now.tv_sec == tv_ref.tv_sec) && (tv_now.tv_usec >= tv_ref.tv_usec)))
>-          waiting = 0;
>+        poll_timeout = (tv_ref.tv_sec-tv_now.tv_sec)*1000 +
>+                       (tv_ref.tv_usec-tv_now.tv_usec)/1000;
>       }
>+
>+      if ((ret = poll(&pollfd, 1, poll_timeout)) != 1)
>+        waiting = 0;
>     }
> 
>     if (context && context != &urb) {

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Attachments on bug 408131: 275191