Fix IO performance regression in sparc
Replace signalfd with signal handler/pipe. There is no way to interrupt the CPU execution loop when a file descriptor becomes readable. This results in a large performance regression in sparc emulation during bootup. This patch switches us to signal handler/pipe which was originally suggested by Ian Jackson. The signal handler lets us interrupt the CPU emulation loop while the write to a pipe lets us avoid the select/signal race condition. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5451 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
parent
235262cf36
commit
9e472e101f
4
Makefile
4
Makefile
|
@ -59,10 +59,6 @@ else
|
|||
BLOCK_OBJS += block-raw-posix.o
|
||||
endif
|
||||
|
||||
ifdef CONFIG_AIO
|
||||
BLOCK_OBJS += compatfd.o
|
||||
endif
|
||||
|
||||
######################################################################
|
||||
# libqemu_common.a: Target independent part of system emulation. The
|
||||
# long term path is to suppress *all* target specific code in case of
|
||||
|
|
|
@ -481,10 +481,6 @@ else
|
|||
OBJS+=block-raw-posix.o
|
||||
endif
|
||||
|
||||
ifdef CONFIG_AIO
|
||||
OBJS+=compatfd.o
|
||||
endif
|
||||
|
||||
LIBS+=-lz
|
||||
ifdef CONFIG_ALSA
|
||||
LIBS += -lasound
|
||||
|
|
|
@ -25,7 +25,6 @@
|
|||
#include "qemu-timer.h"
|
||||
#include "qemu-char.h"
|
||||
#include "block_int.h"
|
||||
#include "compatfd.h"
|
||||
#include <assert.h>
|
||||
#ifdef CONFIG_AIO
|
||||
#include <aio.h>
|
||||
|
@ -453,7 +452,7 @@ typedef struct RawAIOCB {
|
|||
|
||||
typedef struct PosixAioState
|
||||
{
|
||||
int fd;
|
||||
int rfd, wfd;
|
||||
RawAIOCB *first_aio;
|
||||
} PosixAioState;
|
||||
|
||||
|
@ -494,30 +493,17 @@ static void posix_aio_read(void *opaque)
|
|||
PosixAioState *s = opaque;
|
||||
RawAIOCB *acb, **pacb;
|
||||
int ret;
|
||||
size_t offset;
|
||||
union {
|
||||
struct qemu_signalfd_siginfo siginfo;
|
||||
char buf[128];
|
||||
} sig;
|
||||
ssize_t len;
|
||||
|
||||
/* try to read from signalfd, don't freak out if we can't read anything */
|
||||
offset = 0;
|
||||
while (offset < 128) {
|
||||
ssize_t len;
|
||||
do {
|
||||
char byte;
|
||||
|
||||
len = read(s->fd, sig.buf + offset, 128 - offset);
|
||||
len = read(s->rfd, &byte, 1);
|
||||
if (len == -1 && errno == EINTR)
|
||||
continue;
|
||||
if (len == -1 && errno == EAGAIN) {
|
||||
/* there is no natural reason for this to happen,
|
||||
* so we'll spin hard until we get everything just
|
||||
* to be on the safe side. */
|
||||
if (offset > 0)
|
||||
continue;
|
||||
}
|
||||
|
||||
offset += len;
|
||||
}
|
||||
if (len == -1 && errno == EAGAIN)
|
||||
break;
|
||||
} while (len == -1);
|
||||
|
||||
for(;;) {
|
||||
pacb = &s->first_aio;
|
||||
|
@ -565,10 +551,22 @@ static int posix_aio_flush(void *opaque)
|
|||
|
||||
static PosixAioState *posix_aio_state;
|
||||
|
||||
static void aio_signal_handler(int signum)
|
||||
{
|
||||
if (posix_aio_state) {
|
||||
char byte = 0;
|
||||
|
||||
write(posix_aio_state->wfd, &byte, sizeof(byte));
|
||||
}
|
||||
|
||||
qemu_service_io();
|
||||
}
|
||||
|
||||
static int posix_aio_init(void)
|
||||
{
|
||||
sigset_t mask;
|
||||
struct sigaction act;
|
||||
PosixAioState *s;
|
||||
int fds[2];
|
||||
|
||||
if (posix_aio_state)
|
||||
return 0;
|
||||
|
@ -577,21 +575,23 @@ static int posix_aio_init(void)
|
|||
if (s == NULL)
|
||||
return -ENOMEM;
|
||||
|
||||
/* Make sure to block AIO signal */
|
||||
sigemptyset(&mask);
|
||||
sigaddset(&mask, SIGUSR2);
|
||||
sigprocmask(SIG_BLOCK, &mask, NULL);
|
||||
|
||||
sigfillset(&act.sa_mask);
|
||||
act.sa_flags = 0; /* do not restart syscalls to interrupt select() */
|
||||
act.sa_handler = aio_signal_handler;
|
||||
sigaction(SIGUSR2, &act, NULL);
|
||||
|
||||
s->first_aio = NULL;
|
||||
s->fd = qemu_signalfd(&mask);
|
||||
if (s->fd == -1) {
|
||||
fprintf(stderr, "failed to create signalfd\n");
|
||||
if (pipe(fds) == -1) {
|
||||
fprintf(stderr, "failed to create pipe\n");
|
||||
return -errno;
|
||||
}
|
||||
|
||||
fcntl(s->fd, F_SETFL, O_NONBLOCK);
|
||||
s->rfd = fds[0];
|
||||
s->wfd = fds[1];
|
||||
|
||||
qemu_aio_set_fd_handler(s->fd, posix_aio_read, NULL, posix_aio_flush, s);
|
||||
fcntl(s->wfd, F_SETFL, O_NONBLOCK);
|
||||
|
||||
qemu_aio_set_fd_handler(s->rfd, posix_aio_read, NULL, posix_aio_flush, s);
|
||||
|
||||
#if defined(__linux__)
|
||||
{
|
||||
|
|
127
compatfd.c
127
compatfd.c
|
@ -1,127 +0,0 @@
|
|||
/*
|
||||
* signalfd/eventfd compatibility
|
||||
*
|
||||
* Copyright IBM, Corp. 2008
|
||||
*
|
||||
* Authors:
|
||||
* Anthony Liguori <aliguori@us.ibm.com>
|
||||
*
|
||||
* This work is licensed under the terms of the GNU GPL, version 2. See
|
||||
* the COPYING file in the top-level directory.
|
||||
*
|
||||
*/
|
||||
|
||||
#include "qemu-common.h"
|
||||
#include "compatfd.h"
|
||||
|
||||
#include <sys/syscall.h>
|
||||
#include <pthread.h>
|
||||
|
||||
struct sigfd_compat_info
|
||||
{
|
||||
sigset_t mask;
|
||||
int fd;
|
||||
};
|
||||
|
||||
static void *sigwait_compat(void *opaque)
|
||||
{
|
||||
struct sigfd_compat_info *info = opaque;
|
||||
int err;
|
||||
sigset_t all;
|
||||
|
||||
sigfillset(&all);
|
||||
sigprocmask(SIG_BLOCK, &all, NULL);
|
||||
|
||||
do {
|
||||
siginfo_t siginfo;
|
||||
|
||||
err = sigwaitinfo(&info->mask, &siginfo);
|
||||
if (err == -1 && errno == EINTR) {
|
||||
err = 0;
|
||||
continue;
|
||||
}
|
||||
|
||||
if (err > 0) {
|
||||
char buffer[128];
|
||||
size_t offset = 0;
|
||||
|
||||
memcpy(buffer, &err, sizeof(err));
|
||||
while (offset < sizeof(buffer)) {
|
||||
ssize_t len;
|
||||
|
||||
len = write(info->fd, buffer + offset,
|
||||
sizeof(buffer) - offset);
|
||||
if (len == -1 && errno == EINTR)
|
||||
continue;
|
||||
|
||||
if (len <= 0) {
|
||||
err = -1;
|
||||
break;
|
||||
}
|
||||
|
||||
offset += len;
|
||||
}
|
||||
}
|
||||
} while (err >= 0);
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static int qemu_signalfd_compat(const sigset_t *mask)
|
||||
{
|
||||
pthread_attr_t attr;
|
||||
pthread_t tid;
|
||||
struct sigfd_compat_info *info;
|
||||
int fds[2];
|
||||
|
||||
info = malloc(sizeof(*info));
|
||||
if (info == NULL) {
|
||||
errno = ENOMEM;
|
||||
return -1;
|
||||
}
|
||||
|
||||
if (pipe(fds) == -1) {
|
||||
free(info);
|
||||
return -1;
|
||||
}
|
||||
|
||||
memcpy(&info->mask, mask, sizeof(*mask));
|
||||
info->fd = fds[1];
|
||||
|
||||
pthread_attr_init(&attr);
|
||||
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
|
||||
|
||||
pthread_create(&tid, &attr, sigwait_compat, info);
|
||||
|
||||
pthread_attr_destroy(&attr);
|
||||
|
||||
return fds[0];
|
||||
}
|
||||
|
||||
int qemu_signalfd(const sigset_t *mask)
|
||||
{
|
||||
#if defined(CONFIG_signalfd)
|
||||
int ret;
|
||||
|
||||
ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
|
||||
if (ret != -1)
|
||||
return ret;
|
||||
#endif
|
||||
|
||||
return qemu_signalfd_compat(mask);
|
||||
}
|
||||
|
||||
int qemu_eventfd(int *fds)
|
||||
{
|
||||
#if defined(CONFIG_eventfd)
|
||||
int ret;
|
||||
|
||||
ret = syscall(SYS_eventfd, 0);
|
||||
if (ret >= 0) {
|
||||
fds[0] = fds[1] = ret;
|
||||
return 0;
|
||||
}
|
||||
#endif
|
||||
|
||||
return pipe(fds);
|
||||
}
|
28
compatfd.h
28
compatfd.h
|
@ -1,28 +0,0 @@
|
|||
/*
|
||||
* signalfd/eventfd compatibility
|
||||
*
|
||||
* Copyright IBM, Corp. 2008
|
||||
*
|
||||
* Authors:
|
||||
* Anthony Liguori <aliguori@us.ibm.com>
|
||||
*
|
||||
* This work is licensed under the terms of the GNU GPL, version 2. See
|
||||
* the COPYING file in the top-level directory.
|
||||
*
|
||||
*/
|
||||
|
||||
#ifndef QEMU_COMPATFD_H
|
||||
#define QEMU_COMPATFD_H
|
||||
|
||||
#include <signal.h>
|
||||
|
||||
struct qemu_signalfd_siginfo {
|
||||
uint32_t ssi_signo;
|
||||
uint8_t pad[124];
|
||||
};
|
||||
|
||||
int qemu_signalfd(const sigset_t *mask);
|
||||
|
||||
int qemu_eventfd(int *fds);
|
||||
|
||||
#endif
|
|
@ -113,8 +113,6 @@ aio="yes"
|
|||
nptl="yes"
|
||||
mixemu="no"
|
||||
bluez="yes"
|
||||
signalfd="no"
|
||||
eventfd="no"
|
||||
|
||||
# OS specific
|
||||
targetos=`uname -s`
|
||||
|
@ -930,33 +928,6 @@ EOF
|
|||
fi
|
||||
fi
|
||||
|
||||
##########################################
|
||||
# signalfd probe
|
||||
cat > $TMPC << EOF
|
||||
#define _GNU_SOURCE
|
||||
#include <unistd.h>
|
||||
#include <sys/syscall.h>
|
||||
#include <signal.h>
|
||||
int main(void) { return syscall(SYS_signalfd, -1, NULL, _NSIG / 8); }
|
||||
EOF
|
||||
|
||||
if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
|
||||
signalfd=yes
|
||||
fi
|
||||
|
||||
##########################################
|
||||
# eventfd probe
|
||||
cat > $TMPC << EOF
|
||||
#define _GNU_SOURCE
|
||||
#include <unistd.h>
|
||||
#include <sys/syscall.h>
|
||||
int main(void) { return syscall(SYS_eventfd, 0); }
|
||||
EOF
|
||||
|
||||
if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
|
||||
eventfd=yes
|
||||
fi
|
||||
|
||||
# Check if tools are available to build documentation.
|
||||
if [ -x "`which texi2html 2>/dev/null`" ] && \
|
||||
[ -x "`which pod2man 2>/dev/null`" ]; then
|
||||
|
@ -1297,12 +1268,6 @@ if test "$aio" = "yes" ; then
|
|||
echo "#define CONFIG_AIO 1" >> $config_h
|
||||
echo "CONFIG_AIO=yes" >> $config_mak
|
||||
fi
|
||||
if test "$signalfd" = "yes" ; then
|
||||
echo "#define CONFIG_signalfd 1" >> $config_h
|
||||
fi
|
||||
if test "$eventfd" = "yes" ; then
|
||||
echo "#define CONFIG_eventfd 1" >> $config_h
|
||||
fi
|
||||
|
||||
# XXX: suppress that
|
||||
if [ "$bsd" = "yes" ] ; then
|
||||
|
|
|
@ -139,4 +139,7 @@ struct pcmcia_card_s;
|
|||
void cpu_save(QEMUFile *f, void *opaque);
|
||||
int cpu_load(QEMUFile *f, void *opaque, int version_id);
|
||||
|
||||
/* Force QEMU to stop what it's doing and service IO */
|
||||
void qemu_service_io(void);
|
||||
|
||||
#endif
|
||||
|
|
|
@ -26,6 +26,10 @@ struct QEMUBH
|
|||
void *opaque;
|
||||
};
|
||||
|
||||
void qemu_service_io(void)
|
||||
{
|
||||
}
|
||||
|
||||
void term_printf(const char *fmt, ...)
|
||||
{
|
||||
}
|
||||
|
|
13
vl.c
13
vl.c
|
@ -7475,6 +7475,19 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
|
|||
return 0;
|
||||
}
|
||||
|
||||
void qemu_service_io(void)
|
||||
{
|
||||
CPUState *env = cpu_single_env;
|
||||
if (env) {
|
||||
cpu_interrupt(env, CPU_INTERRUPT_EXIT);
|
||||
#ifdef USE_KQEMU
|
||||
if (env->kqemu_enabled) {
|
||||
kqemu_cpu_interrupt(env);
|
||||
}
|
||||
#endif
|
||||
}
|
||||
}
|
||||
|
||||
/***********************************************************/
|
||||
/* bottom halves (can be seen as timers which expire ASAP) */
|
||||
|
||||
|
|
Loading…
Reference in New Issue