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Re: [Qemu-devel] [RFC 08/29] migration: reuse mis->userfault_quit_fd
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC 08/29] migration: reuse mis->userfault_quit_fd |
Date: |
Mon, 31 Jul 2017 19:42:45 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Peter Xu (address@hidden) wrote:
> It was only used for quitting the page fault thread before. Let it be
> something more useful - now we can use it to notify a "wake" for the
> page fault thread (for any reason), and it only means "quit" if the
> fault_thread_quit is set.
>
> Since we changed what it does, renaming it to userfault_event_fd.
>
> Signed-off-by: Peter Xu <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> ---
> migration/migration.h | 6 ++++--
> migration/postcopy-ram.c | 24 ++++++++++++++++--------
> 2 files changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/migration/migration.h b/migration/migration.h
> index 148c9fa..70e3094 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -35,6 +35,8 @@ struct MigrationIncomingState {
> bool have_fault_thread;
> QemuThread fault_thread;
> QemuSemaphore fault_thread_sem;
> + /* Set this when we want the fault thread to quit */
> + bool fault_thread_quit;
>
> bool have_listen_thread;
> QemuThread listen_thread;
> @@ -42,8 +44,8 @@ struct MigrationIncomingState {
>
> /* For the kernel to send us notifications */
> int userfault_fd;
> - /* To tell the fault_thread to quit */
> - int userfault_quit_fd;
> + /* To notify the fault_thread to wake, e.g., when need to quit */
> + int userfault_event_fd;
> QEMUFile *to_src_file;
> QemuMutex rp_mutex; /* We send replies from multiple threads */
> void *postcopy_tmp_page;
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 952b73a..4278fe7 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -305,7 +305,8 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
> *mis)
> * currently be at 0, we're going to increment it to 1
> */
> tmp64 = 1;
> - if (write(mis->userfault_quit_fd, &tmp64, 8) == 8) {
> + atomic_set(&mis->fault_thread_quit, 1);
> + if (write(mis->userfault_event_fd, &tmp64, 8) == 8) {
> trace_postcopy_ram_incoming_cleanup_join();
> qemu_thread_join(&mis->fault_thread);
> } else {
> @@ -315,7 +316,7 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
> *mis)
> }
> trace_postcopy_ram_incoming_cleanup_closeuf();
> close(mis->userfault_fd);
> - close(mis->userfault_quit_fd);
> + close(mis->userfault_event_fd);
> mis->have_fault_thread = false;
> }
>
> @@ -438,7 +439,7 @@ static void *postcopy_ram_fault_thread(void *opaque)
> pfd[0].fd = mis->userfault_fd;
> pfd[0].events = POLLIN;
> pfd[0].revents = 0;
> - pfd[1].fd = mis->userfault_quit_fd;
> + pfd[1].fd = mis->userfault_event_fd;
> pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
> pfd[1].revents = 0;
>
> @@ -448,8 +449,15 @@ static void *postcopy_ram_fault_thread(void *opaque)
> }
>
> if (pfd[1].revents) {
> - trace_postcopy_ram_fault_thread_quit();
> - break;
> + uint64_t tmp64 = 0;
> +
> + /* Consume the signal */
> + read(mis->userfault_event_fd, &tmp64, 8);
> +
> + if (atomic_read(&mis->fault_thread_quit)) {
> + trace_postcopy_ram_fault_thread_quit();
> + break;
> + }
> }
>
> ret = read(mis->userfault_fd, &msg, sizeof(msg));
> @@ -528,9 +536,9 @@ int postcopy_ram_enable_notify(MigrationIncomingState
> *mis)
> }
>
> /* Now an eventfd we use to tell the fault-thread to quit */
> - mis->userfault_quit_fd = eventfd(0, EFD_CLOEXEC);
> - if (mis->userfault_quit_fd == -1) {
> - error_report("%s: Opening userfault_quit_fd: %s", __func__,
> + mis->userfault_event_fd = eventfd(0, EFD_CLOEXEC);
> + if (mis->userfault_event_fd == -1) {
> + error_report("%s: Opening userfault_event_fd: %s", __func__,
> strerror(errno));
> close(mis->userfault_fd);
> return -1;
> --
> 2.7.4
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [RFC 03/29] io: fix qio_channel_socket_accept err handling, (continued)
- [Qemu-devel] [RFC 04/29] bitmap: introduce bitmap_invert(), Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 05/29] bitmap: introduce bitmap_count_one(), Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 06/29] migration: dump str in migrate_set_state trace, Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 08/29] migration: reuse mis->userfault_quit_fd, Peter Xu, 2017/07/28
- Re: [Qemu-devel] [RFC 08/29] migration: reuse mis->userfault_quit_fd,
Dr. David Alan Gilbert <=
- [Qemu-devel] [RFC 07/29] migration: better error handling with QEMUFile, Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 09/29] migration: provide postcopy_fault_thread_notify(), Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 10/29] migration: new property "x-postcopy-fast", Peter Xu, 2017/07/28
- [Qemu-devel] [RFC 11/29] migration: new postcopy-pause state, Peter Xu, 2017/07/28