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use eventfd for iothread

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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Paolo Bonzini 2010-02-11 00:23:46 +01:00 committed by Avi Kivity
parent bf76bafa5a
commit f3dfda6114
3 changed files with 38 additions and 4 deletions
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32
osdep.c
View File

@ -37,6 +37,10 @@
#include <sys/statvfs.h> #include <sys/statvfs.h>
#endif #endif
#ifdef CONFIG_EVENTFD
#include <sys/eventfd.h>
#endif
#ifdef _WIN32 #ifdef _WIN32
#include <windows.h> #include <windows.h>
#elif defined(CONFIG_BSD) #elif defined(CONFIG_BSD)
@ -280,6 +284,34 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
} }
#ifndef _WIN32 #ifndef _WIN32
/*
* Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
*/
int qemu_eventfd(int fds[2])
{
int ret;
#ifdef CONFIG_EVENTFD
ret = eventfd(0, 0);
if (ret >= 0) {
fds[0] = ret;
qemu_set_cloexec(ret);
if ((fds[1] = dup(ret)) == -1) {
close(ret);
return -1;
}
qemu_set_cloexec(fds[1]);
return 0;
}
if (errno != ENOSYS) {
return -1;
}
#endif
return qemu_pipe(fds);
}
/* /*
* Creates a pipe with FD_CLOEXEC set on both file descriptors * Creates a pipe with FD_CLOEXEC set on both file descriptors
*/ */

1
qemu-common.h
View File

@ -170,6 +170,7 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
void qemu_set_cloexec(int fd); void qemu_set_cloexec(int fd);
#ifndef _WIN32 #ifndef _WIN32
int qemu_eventfd(int pipefd[2]);
int qemu_pipe(int pipefd[2]); int qemu_pipe(int pipefd[2]);
#endif #endif

9
vl.c
View File

@ -3211,14 +3211,15 @@ static int io_thread_fd = -1;
static void qemu_event_increment(void) static void qemu_event_increment(void)
{ {
static const char byte = 0; /* Write 8 bytes to be compatible with eventfd. */
static uint64_t val = 1;
ssize_t ret; ssize_t ret;
if (io_thread_fd == -1) if (io_thread_fd == -1)
return; return;
do { do {
ret = write(io_thread_fd, &byte, sizeof(byte)); ret = write(io_thread_fd, &val, sizeof(val));
} while (ret < 0 && errno == EINTR); } while (ret < 0 && errno == EINTR);
/* EAGAIN is fine, a read must be pending. */ /* EAGAIN is fine, a read must be pending. */
@ -3235,7 +3236,7 @@ static void qemu_event_read(void *opaque)
ssize_t len; ssize_t len;
char buffer[512]; char buffer[512];
/* Drain the notify pipe */ /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
do { do {
len = read(fd, buffer, sizeof(buffer)); len = read(fd, buffer, sizeof(buffer));
} while ((len == -1 && errno == EINTR) || len == sizeof(buffer)); } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
@ -3246,7 +3247,7 @@ static int qemu_event_init(void)
int err; int err;
int fds[2]; int fds[2];
err = qemu_pipe(fds); err = qemu_eventfd(fds);
if (err == -1) if (err == -1)
return -errno; return -errno;