commit d3e13a91224d167652288ba98de15658a233d60e Author: Anthony Liguori Date: Tue Oct 7 17:21:38 2008 -0500 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 diff --git a/compatfd.c b/compatfd.c deleted file mode 100644 index cc5ced3..0000000 --- a/compatfd.c +++ /dev/null @@ -1,127 +0,0 @@ -/* - * signalfd/eventfd compatibility - * - * Copyright IBM, Corp. 2008 - * - * Authors: - * Anthony Liguori - * - * 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 -#include - -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); -} diff --git a/compatfd.h b/compatfd.h deleted file mode 100644 index 55a111a..0000000 --- a/compatfd.h +++ /dev/null @@ -1,28 +0,0 @@ -/* - * signalfd/eventfd compatibility - * - * Copyright IBM, Corp. 2008 - * - * Authors: - * Anthony Liguori - * - * 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 - -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