From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:57123) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R5fN6-0000gU-Hj for qemu-devel@nongnu.org; Mon, 19 Sep 2011 11:03:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R5fN5-0008Ch-0R for qemu-devel@nongnu.org; Mon, 19 Sep 2011 11:03:00 -0400 Received: from mail-ww0-f53.google.com ([74.125.82.53]:33296) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R5fN4-0008CL-JI for qemu-devel@nongnu.org; Mon, 19 Sep 2011 11:02:58 -0400 Received: by wwg14 with SMTP id 14so7079174wwg.10 for ; Mon, 19 Sep 2011 08:02:57 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <4E775999.7060008@redhat.com> Date: Mon, 19 Sep 2011 17:02:49 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1316443033-6489-1-git-send-email-freddy77@gmail.com> In-Reply-To: <1316443033-6489-1-git-send-email-freddy77@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] block: avoid SIGUSR2 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Frediano Ziglio Cc: kwolf@redhat.com, aliguori@us.ibm.com, qemu-devel@nongnu.org On 09/19/2011 04:37 PM, Frediano Ziglio wrote: > Now that iothread is always compiled sending a signal seems only an > additional step. This patch also avoid writing to two pipe (one from signal > and one in qemu_service_io). > > Work with kvm enabled or disabled. strace output is more readable (less syscalls). > > Signed-off-by: Frediano Ziglio > --- > cpus.c | 5 ----- > posix-aio-compat.c | 29 +++++++++-------------------- > 2 files changed, 9 insertions(+), 25 deletions(-) > > diff --git a/cpus.c b/cpus.c > index 54c188c..d0cfe91 100644 > --- a/cpus.c > +++ b/cpus.c > @@ -380,11 +380,6 @@ static int qemu_signal_init(void) > int sigfd; > sigset_t set; > > - /* SIGUSR2 used by posix-aio-compat.c */ > - sigemptyset(&set); > - sigaddset(&set, SIGUSR2); > - pthread_sigmask(SIG_UNBLOCK,&set, NULL); > - > /* > * SIG_IPI must be blocked in the main thread and must not be caught > * by sigwait() in the signal thread. Otherwise, the cpu thread will > diff --git a/posix-aio-compat.c b/posix-aio-compat.c > index 3193dbf..185d5b2 100644 > --- a/posix-aio-compat.c > +++ b/posix-aio-compat.c > @@ -42,7 +42,6 @@ struct qemu_paiocb { > int aio_niov; > size_t aio_nbytes; > #define aio_ioctl_cmd aio_nbytes /* for QEMU_AIO_IOCTL */ > - int ev_signo; > off_t aio_offset; > > QTAILQ_ENTRY(qemu_paiocb) node; > @@ -309,6 +308,8 @@ static ssize_t handle_aiocb_rw(struct qemu_paiocb *aiocb) > return nbytes; > } > > +static void posix_aio_notify_event(void); > + > static void *aio_thread(void *unused) > { > pid_t pid; > @@ -381,7 +382,7 @@ static void *aio_thread(void *unused) > aiocb->ret = ret; > mutex_unlock(&lock); > > - if (kill(pid, aiocb->ev_signo)) die("kill failed"); > + posix_aio_notify_event(); > } > > cur_threads--; > @@ -548,18 +549,14 @@ static int posix_aio_flush(void *opaque) > > static PosixAioState *posix_aio_state; > > -static void aio_signal_handler(int signum) > +static void posix_aio_notify_event(void) > { > - if (posix_aio_state) { > - char byte = 0; > - ssize_t ret; > - > - ret = write(posix_aio_state->wfd,&byte, sizeof(byte)); > - if (ret< 0&& errno != EAGAIN) > - die("write()"); > - } > + char byte = 0; > + ssize_t ret; > > - qemu_service_io(); > + ret = write(posix_aio_state->wfd,&byte, sizeof(byte)); > + if (ret< 0&& errno != EAGAIN) > + die("write()"); > } > > static void paio_remove(struct qemu_paiocb *acb) > @@ -623,7 +620,6 @@ BlockDriverAIOCB *paio_submit(BlockDriverState *bs, int fd, > return NULL; > acb->aio_type = type; > acb->aio_fildes = fd; > - acb->ev_signo = SIGUSR2; > > if (qiov) { > acb->aio_iov = qiov->iov; > @@ -651,7 +647,6 @@ BlockDriverAIOCB *paio_ioctl(BlockDriverState *bs, int fd, > return NULL; > acb->aio_type = QEMU_AIO_IOCTL; > acb->aio_fildes = fd; > - acb->ev_signo = SIGUSR2; > acb->aio_offset = 0; > acb->aio_ioctl_buf = buf; > acb->aio_ioctl_cmd = req; > @@ -665,7 +660,6 @@ BlockDriverAIOCB *paio_ioctl(BlockDriverState *bs, int fd, > > int paio_init(void) > { > - struct sigaction act; > PosixAioState *s; > int fds[2]; > int ret; > @@ -675,11 +669,6 @@ int paio_init(void) > > s = g_malloc(sizeof(PosixAioState)); > > - 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; > if (qemu_pipe(fds) == -1) { > fprintf(stderr, "failed to create pipe\n"); I think it is possible to go a step further, turn posix_aio_process_queue into a bottom half and get rid of the pipe altogether. This in turn would remove the only real user of io_process_queue in qemu_aio_set_fd_handler. However, this is already a nice improvement. Reviewed-by: Paolo Bonzini