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Re: [Qemu-devel] [PATCH 13/13] migration: flush receive queue
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 13/13] migration: flush receive queue |
Date: |
Wed, 26 Oct 2016 20:10:31 +0100 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
* Juan Quintela (address@hidden) wrote:
> From: Juan Quintela <address@hidden>
>
> Each time that we sync the bitmap, it is a possiblity that we receive
> a page that is being processed by a different thread. We fix this
> problem just making sure that we wait for all receiving threads to
> finish its work before we procedeed with the next stage.
>
> I tried to make a migration command for it, but it don't work because
> we sync the bitmap sometimes when we have already sent the beggining
> of the section, so I just added a new page flag.
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> include/migration/migration.h | 1 +
> migration/ram.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index afdc7ec..49e2ec6 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -251,6 +251,7 @@ void migrate_multifd_send_threads_create(void);
> void migrate_multifd_send_threads_join(void);
> void migrate_multifd_recv_threads_create(void);
> void migrate_multifd_recv_threads_join(void);
> +void qemu_savevm_send_multifd_flush(QEMUFile *f);
>
> void migrate_compress_threads_create(void);
> void migrate_compress_threads_join(void);
> diff --git a/migration/ram.c b/migration/ram.c
> index 9a20f63..bf2022e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -69,6 +69,7 @@ static uint64_t bitmap_sync_count;
> /* 0x80 is reserved in migration.h start with 0x100 next */
> #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
> #define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200
> +#define RAM_SAVE_FLAG_MULTIFD_FLUSH 0x400
Now you really have run out of flags; there are architectures
with 1kB target pages.
However, we really just shouldn't be gobbling these flags up;
the flush could be MULTIFD_PAGE | one of the other flags.
Dave
> static const uint8_t ZERO_TARGET_PAGE[TARGET_PAGE_SIZE];
>
> @@ -398,6 +399,11 @@ void migrate_compress_threads_create(void)
>
> /* Multiple fd's */
>
> +
> +/* Indicates if we have synced the bitmap and we need to assure that
> + target has processeed all previous pages */
> +bool multifd_needs_flush = false;
> +
> struct MultiFDSendParams {
> /* not changed */
> QemuThread thread;
> @@ -713,6 +719,25 @@ static void multifd_recv_page(uint8_t *address, int
> fd_num)
> qemu_mutex_unlock(¶ms->mutex);
> }
>
> +
> +static int multifd_flush(void)
> +{
> + int i, thread_count;
> +
> + if (!migrate_multifd()) {
> + return 0;
> + }
> + thread_count = migrate_multifd_threads();
> + qemu_mutex_lock(&multifd_recv_mutex);
> + for (i = 0; i < thread_count; i++) {
> + while(!multifd_recv[i].done) {
> + qemu_cond_wait(&multifd_recv_cond, &multifd_recv_mutex);
> + }
> + }
> + qemu_mutex_unlock(&multifd_recv_mutex);
> + return 0;
> +}
> +
> /**
> * save_page_header: Write page header to wire
> *
> @@ -729,6 +754,11 @@ static size_t save_page_header(QEMUFile *f, RAMBlock
> *block, ram_addr_t offset)
> {
> size_t size, len;
>
> + if (multifd_needs_flush) {
> + offset |= RAM_SAVE_FLAG_MULTIFD_FLUSH;
> + multifd_needs_flush = false;
> + }
> +
> qemu_put_be64(f, offset);
> size = 8;
>
> @@ -2399,6 +2429,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>
> if (!migration_in_postcopy(migrate_get_current())) {
> migration_bitmap_sync();
> + if (migrate_multifd()) {
> + multifd_needs_flush = true;
> + }
> }
>
> ram_control_before_iterate(f, RAM_CONTROL_FINISH);
> @@ -2440,6 +2473,9 @@ static void ram_save_pending(QEMUFile *f, void *opaque,
> uint64_t max_size,
> qemu_mutex_lock_iothread();
> rcu_read_lock();
> migration_bitmap_sync();
> + if (migrate_multifd()) {
> + multifd_needs_flush = true;
> + }
> rcu_read_unlock();
> qemu_mutex_unlock_iothread();
> remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
> @@ -2851,6 +2887,10 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> flags = addr & ~TARGET_PAGE_MASK;
> addr &= TARGET_PAGE_MASK;
>
> + if (flags & RAM_SAVE_FLAG_MULTIFD_FLUSH) {
> + multifd_flush();
> + flags = flags & (~RAM_SAVE_FLAG_MULTIFD_FLUSH);
> + }
> if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE |
> RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE |
> RAM_SAVE_FLAG_MULTIFD_PAGE)) {
> --
> 2.7.4
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH 06/13] migration: Start of multiple fd work, (continued)
- [Qemu-devel] [PATCH 06/13] migration: Start of multiple fd work, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 07/13] migration: create ram_multifd_page, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 09/13] migration: Send the fd number which we are going to use for this page, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 08/13] migration: Create thread infrastructure for multifd send side, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 11/13] migration: Test new fd infrastructure, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 10/13] migration: Create thread infrastructure for multifd recv side, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 12/13] migration: [HACK]Transfer pages over new channels, Juan Quintela, 2016/10/21
- [Qemu-devel] [PATCH 13/13] migration: flush receive queue, Juan Quintela, 2016/10/21
- Re: [Qemu-devel] [PATCH 13/13] migration: flush receive queue,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [RFC 00/13] Multifd v2, no-reply, 2016/10/21