Re: [PATCH v2 05/16] migration: Move rate_limit_max and rate_limit_used to migration_stats

[Cédric Le Goater]

On 5/15/23 21:56, Juan Quintela wrote:
> These way we can make them atomic and use this functions from any
> place.  I also moved all functions that use rate_limit to
> migration-stats.
>
> Functions got renamed, they are not qemu_file anymore.
>
> qemu_file_rate_limit -> migration_rate_exceeded
> qemu_file_set_rate_limit -> migration_rate_set
> qemu_file_get_rate_limit -> migration_rate_get
> qemu_file_reset_rate_limit -> migration_rate_reset
> qemu_file_acct_rate_limit -> migration_rate_account.
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.


> ---
>
> s/this/these/ (harsh)
> If you have any good suggestion for better names, I am all ears.
> Fix missing / XFER_LIMIT_RATIO in migration_rate_set(quintela)
> ---
>   include/migration/qemu-file-types.h | 12 ++++++-
>   migration/migration-stats.h         | 47 ++++++++++++++++++++++++++
>   migration/options.h                 |  7 ----
>   migration/qemu-file.h               | 11 ------
>   hw/ppc/spapr.c                      |  4 +--
>   hw/s390x/s390-stattrib.c            |  2 +-
>   migration/block-dirty-bitmap.c      |  2 +-
>   migration/block.c                   |  5 +--
>   migration/migration-stats.c         | 44 ++++++++++++++++++++++++
>   migration/migration.c               | 14 ++++----
>   migration/multifd.c                 |  2 +-
>   migration/options.c                 |  7 ++--
>   migration/qemu-file.c               | 52 ++---------------------------
>   migration/ram.c                     |  2 +-
>   migration/savevm.c                  |  2 +-
>   15 files changed, 124 insertions(+), 89 deletions(-)
>
> diff --git a/include/migration/qemu-file-types.h 
> b/include/migration/qemu-file-types.h
> index 1436f9ce92..9ba163f333 100644
> --- a/include/migration/qemu-file-types.h
> +++ b/include/migration/qemu-file-types.h
> @@ -165,6 +165,16 @@ size_t coroutine_mixed_fn qemu_get_counted_string(QEMUFile 
> *f, char buf[256]);
>   
>   void qemu_put_counted_string(QEMUFile *f, const char *name);
>   
> -int qemu_file_rate_limit(QEMUFile *f);
> +/**
> + * migration_rate_exceeded: Check if we have exceeded rate for this interval
> + *
> + * Checks if we have already transferred more data that we are allowed
> + * in the current interval.
> + *
> + * @f: QEMUFile used for main migration channel
> + *
> + * Returns if we should stop sending data for this interval.
> + */
> +bool migration_rate_exceeded(QEMUFile *f);
>   
>   #endif
> diff --git a/migration/migration-stats.h b/migration/migration-stats.h
> index 21402af9e4..e39c083245 100644
> --- a/migration/migration-stats.h
> +++ b/migration/migration-stats.h
> @@ -15,6 +15,12 @@
>   
>   #include "qemu/stats64.h"
>   
> +/*
> + * Amount of time to allocate to each "chunk" of bandwidth-throttled
> + * data.
> + */
> +#define BUFFER_DELAY     100
> +
>   /*
>    * If rate_limit_max is 0, there is special code to remove the rate
>    * limit.
> @@ -75,6 +81,14 @@ typedef struct {
>        * Number of bytes sent during precopy stage.
>        */
>       Stat64 precopy_bytes;
> +    /*
> +     * Maximum amount of data we can send in a cycle.
> +     */
> +    Stat64 rate_limit_max;
> +    /*
> +     * Amount of data we have sent in the current cycle.
> +     */
> +    Stat64 rate_limit_used;
>       /*
>        * How long has the setup stage took.
>        */
> @@ -100,4 +114,37 @@ extern MigrationAtomicStats mig_stats;
>    * Returns: Nothing.  The time is stored in val.
>    */
>   void migration_time_since(MigrationAtomicStats *stats, int64_t since);
> +
> +/**
> + * migration_rate_account: Increase the number of bytes transferred.
> + *
> + * Report on a number of bytes the have been transferred that need to
> + * be applied to the rate limiting calcuations.
> + *
> + * @len: amount of bytes transferred
> + */
> +void migration_rate_account(uint64_t len);
> +
> +/**
> + * migration_rate_get: Get the maximum amount that can be transferred.
> + *
> + * Returns the maximum number of bytes that can be transferred in a cycle.
> + */
> +uint64_t migration_rate_get(void);
> +
> +/**
> + * migration_rate_reset: Reset the rate limit counter.
> + *
> + * This is called when we know we start a new transfer cycle.
> + */
> +void migration_rate_reset(void);
> +
> +/**
> + * migration_rate_set: Set the maximum amount that can be transferred.
> + *
> + * Sets the maximum amount of bytes that can be transferred in one cycle.
> + *
> + * @new_rate: new maximum amount
> + */
> +void migration_rate_set(uint64_t new_rate);
>   #endif
> diff --git a/migration/options.h b/migration/options.h
> index 5cca3326d6..45991af3c2 100644
> --- a/migration/options.h
> +++ b/migration/options.h
> @@ -17,13 +17,6 @@
>   #include "hw/qdev-properties.h"
>   #include "hw/qdev-properties-system.h"
>   
> -/* constants */
> -
> -/* Amount of time to allocate to each "chunk" of bandwidth-throttled
> - * data. */
> -#define BUFFER_DELAY     100
> -#define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
> -
>   /* migration properties */
>   
>   extern Property migration_properties[];
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index bcc39081f2..e649718492 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -130,17 +130,6 @@ void qemu_file_skip(QEMUFile *f, int size);
>    * accounting information tracks the total migration traffic.
>    */
>   void qemu_file_credit_transfer(QEMUFile *f, size_t size);
> -void qemu_file_reset_rate_limit(QEMUFile *f);
> -/*
> - * qemu_file_acct_rate_limit:
> - *
> - * Report on a number of bytes the have been transferred
> - * out of band from the main file object I/O methods, and
> - * need to be applied to the rate limiting calcuations
> - */
> -void qemu_file_acct_rate_limit(QEMUFile *f, uint64_t len);
> -void qemu_file_set_rate_limit(QEMUFile *f, uint64_t new_rate);
> -uint64_t qemu_file_get_rate_limit(QEMUFile *f);
>   int qemu_file_get_error_obj(QEMUFile *f, Error **errp);
>   int qemu_file_get_error_obj_any(QEMUFile *f1, QEMUFile *f2, Error **errp);
>   void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err);
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index ddc9c7b1a1..1baea16c96 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2166,7 +2166,7 @@ static void htab_save_first_pass(QEMUFile *f, 
> SpaprMachineState *spapr,
>                   break;
>               }
>           }
> -    } while ((index < htabslots) && !qemu_file_rate_limit(f));
> +    } while ((index < htabslots) && !migration_rate_exceeded(f));
>   
>       if (index >= htabslots) {
>           assert(index == htabslots);
> @@ -2237,7 +2237,7 @@ static int htab_save_later_pass(QEMUFile *f, 
> SpaprMachineState *spapr,
>               assert(index == htabslots);
>               index = 0;
>           }
> -    } while ((examined < htabslots) && (!qemu_file_rate_limit(f) || final));
> +    } while ((examined < htabslots) && (!migration_rate_exceeded(f) || final));
>   
>       if (index >= htabslots) {
>           assert(index == htabslots);
> diff --git a/hw/s390x/s390-stattrib.c b/hw/s390x/s390-stattrib.c
> index aed919ad7d..220e845d12 100644
> --- a/hw/s390x/s390-stattrib.c
> +++ b/hw/s390x/s390-stattrib.c
> @@ -209,7 +209,7 @@ static int cmma_save(QEMUFile *f, void *opaque, int final)
>           return -ENOMEM;
>       }
>   
> -    while (final ? 1 : qemu_file_rate_limit(f) == 0) {
> +    while (final ? 1 : migration_rate_exceeded(f) == 0) {
>           reallen = sac->get_stattr(sas, &start_gfn, buflen, buf);
>           if (reallen < 0) {
>               g_free(buf);
> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> index 20f36e6bd8..032fc5f405 100644
> --- a/migration/block-dirty-bitmap.c
> +++ b/migration/block-dirty-bitmap.c
> @@ -706,7 +706,7 @@ static void bulk_phase(QEMUFile *f, DBMSaveState *s, bool 
> limit)
>       QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
>           while (!dbms->bulk_completed) {
>               bulk_phase_send_chunk(f, s, dbms);
> -            if (limit && qemu_file_rate_limit(f)) {
> +            if (limit && migration_rate_exceeded(f)) {
>                   return;
>               }
>           }
> diff --git a/migration/block.c b/migration/block.c
> index 12617b4152..b9580a6c7e 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -23,6 +23,7 @@
>   #include "block/dirty-bitmap.h"
>   #include "migration/misc.h"
>   #include "migration.h"
> +#include "migration-stats.h"
>   #include "migration/register.h"
>   #include "qemu-file.h"
>   #include "migration/vmstate.h"
> @@ -625,7 +626,7 @@ static int flush_blks(QEMUFile *f)
>   
>       blk_mig_lock();
>       while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
> -        if (qemu_file_rate_limit(f)) {
> +        if (migration_rate_exceeded(f)) {
>               break;
>           }
>           if (blk->ret < 0) {
> @@ -762,7 +763,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
>       /* control the rate of transfer */
>       blk_mig_lock();
>       while (block_mig_state.read_done * BLK_MIG_BLOCK_SIZE <
> -           qemu_file_get_rate_limit(f) &&
> +           migration_rate_get() &&
>              block_mig_state.submitted < MAX_PARALLEL_IO &&
>              (block_mig_state.submitted + block_mig_state.read_done) <
>              MAX_IO_BUFFERS) {
> diff --git a/migration/migration-stats.c b/migration/migration-stats.c
> index 3431453c90..1b16edae7d 100644
> --- a/migration/migration-stats.c
> +++ b/migration/migration-stats.c
> @@ -13,6 +13,7 @@
>   #include "qemu/osdep.h"
>   #include "qemu/stats64.h"
>   #include "qemu/timer.h"
> +#include "qemu-file.h"
>   #include "migration-stats.h"
>   
>   MigrationAtomicStats mig_stats;
> @@ -22,3 +23,46 @@ void migration_time_since(MigrationAtomicStats *stats, 
> int64_t since)
>       int64_t now = qemu_clock_get_ms(QEMU_CLOCK_HOST);
>       stat64_set(&stats->setup_time, now - since);
>   }
> +
> +bool migration_rate_exceeded(QEMUFile *f)
> +{
> +    if (qemu_file_get_error(f)) {
> +        return true;
> +    }
> +
> +    uint64_t rate_limit_used = stat64_get(&mig_stats.rate_limit_used);
> +    uint64_t rate_limit_max = stat64_get(&mig_stats.rate_limit_max);
> +
> +    if (rate_limit_max == RATE_LIMIT_MAX) {
> +        return false;
> +    }
> +    if (rate_limit_max > 0 && rate_limit_used > rate_limit_max) {
> +        return true;
> +    }
> +    return false;
> +}
> +
> +uint64_t migration_rate_get(void)
> +{
> +    return stat64_get(&mig_stats.rate_limit_max);
> +}
> +
> +#define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
> +
> +void migration_rate_set(uint64_t limit)
> +{
> +    /*
> +     * 'limit' is per second.  But we check it each BUFER_DELAY miliseconds.
> +     */
> +    stat64_set(&mig_stats.rate_limit_max, limit / XFER_LIMIT_RATIO);
> +}
> +
> +void migration_rate_reset(void)
> +{
> +    stat64_set(&mig_stats.rate_limit_used, 0);
> +}
> +
> +void migration_rate_account(uint64_t len)
> +{
> +    stat64_add(&mig_stats.rate_limit_used, len);
> +}
> diff --git a/migration/migration.c b/migration/migration.c
> index e9466273bb..594709dbbc 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2119,7 +2119,7 @@ static int postcopy_start(MigrationState *ms)
>        * will notice we're in POSTCOPY_ACTIVE and not actually
>        * wrap their state up here
>        */
> -    qemu_file_set_rate_limit(ms->to_dst_file, bandwidth);
> +    migration_rate_set(bandwidth);
>       if (migrate_postcopy_ram()) {
>           /* Ping just for debugging, helps line traces up */
>           qemu_savevm_send_ping(ms->to_dst_file, 2);
> @@ -2303,7 +2303,7 @@ static void migration_completion(MigrationState *s)
>                    * them if migration fails or is cancelled.
>                    */
>                   s->block_inactive = !migrate_colo();
> -                qemu_file_set_rate_limit(s->to_dst_file, RATE_LIMIT_MAX);
> +                migration_rate_set(RATE_LIMIT_MAX);
>                   ret = qemu_savevm_state_complete_precopy(s->to_dst_file, 
> false,
>                                                            s->block_inactive);
>               }
> @@ -2698,7 +2698,7 @@ static void migration_update_counters(MigrationState *s,
>               stat64_get(&mig_stats.dirty_bytes_last_sync) / bandwidth;
>       }
>   
> -    qemu_file_reset_rate_limit(s->to_dst_file);
> +    migration_rate_reset();
>   
>       update_iteration_initial_status(s);
>   
> @@ -2851,7 +2851,7 @@ bool migration_rate_limit(void)
>   
>       bool urgent = false;
>       migration_update_counters(s, now);
> -    if (qemu_file_rate_limit(s->to_dst_file)) {
> +    if (migration_rate_exceeded(s->to_dst_file)) {
>   
>           if (qemu_file_get_error(s->to_dst_file)) {
>               return false;
> @@ -2973,7 +2973,7 @@ static void *migration_thread(void *opaque)
>       trace_migration_thread_setup_complete();
>   
>       while (migration_is_active(s)) {
> -        if (urgent || !qemu_file_rate_limit(s->to_dst_file)) {
> +        if (urgent || !migration_rate_exceeded(s->to_dst_file)) {
>               MigIterateState iter_state = migration_iteration_run(s);
>               if (iter_state == MIG_ITERATE_SKIP) {
>                   continue;
> @@ -3047,7 +3047,7 @@ static void *bg_migration_thread(void *opaque)
>       rcu_register_thread();
>       object_ref(OBJECT(s));
>   
> -    qemu_file_set_rate_limit(s->to_dst_file, RATE_LIMIT_MAX);
> +    migration_rate_set(RATE_LIMIT_MAX);
>   
>       setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
>       /*
> @@ -3219,7 +3219,7 @@ void migrate_fd_connect(MigrationState *s, Error 
> *error_in)
>           notifier_list_notify(&migration_state_notifiers, s);
>       }
>   
> -    qemu_file_set_rate_limit(s->to_dst_file, rate_limit);
> +    migration_rate_set(rate_limit);
>       qemu_file_set_blocking(s->to_dst_file, true);
>   
>       /*
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 5c4298eadf..5052091ce2 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -431,7 +431,7 @@ static int multifd_send_pages(QEMUFile *f)
>       multifd_send_state->pages = p->pages;
>       p->pages = pages;
>       transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
> -    qemu_file_acct_rate_limit(f, transferred);
> +    migration_rate_account(transferred);
>       qemu_mutex_unlock(&p->mutex);
>       stat64_add(&mig_stats.transferred, transferred);
>       stat64_add(&mig_stats.multifd_bytes, transferred);
> diff --git a/migration/options.c b/migration/options.c
> index c2a278ee2d..b62ab30cd5 100644
> --- a/migration/options.c
> +++ b/migration/options.c
> @@ -23,6 +23,7 @@
>   #include "migration/colo.h"
>   #include "migration/misc.h"
>   #include "migration.h"
> +#include "migration-stats.h"
>   #include "qemu-file.h"
>   #include "ram.h"
>   #include "options.h"
> @@ -1242,8 +1243,7 @@ static void migrate_params_apply(MigrateSetParameters 
> *params, Error **errp)
>       if (params->has_max_bandwidth) {
>           s->parameters.max_bandwidth = params->max_bandwidth;
>           if (s->to_dst_file && !migration_in_postcopy()) {
> -            qemu_file_set_rate_limit(s->to_dst_file,
> -                                s->parameters.max_bandwidth);
> +            migration_rate_set(s->parameters.max_bandwidth);
>           }
>       }
>   
> @@ -1272,8 +1272,7 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
>       if (params->has_max_postcopy_bandwidth) {
>           s->parameters.max_postcopy_bandwidth = params->max_postcopy_bandwidth;
>           if (s->to_dst_file && migration_in_postcopy()) {
> -            qemu_file_set_rate_limit(s->to_dst_file,
> -                    s->parameters.max_postcopy_bandwidth);
> +            migration_rate_set(s->parameters.max_postcopy_bandwidth);
>           }
>       }
>       if (params->has_max_cpu_throttle) {
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index 956bd2a580..9c67b52fe0 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -41,17 +41,6 @@ struct QEMUFile {
>       QIOChannel *ioc;
>       bool is_writable;
>   
> -    /*
> -     * Maximum amount of data in bytes to transfer during one
> -     * rate limiting time window
> -     */
> -    uint64_t rate_limit_max;
> -    /*
> -     * Total amount of data in bytes queued for transfer
> -     * during this rate limiting time window
> -     */
> -    uint64_t rate_limit_used;
> -
>       /* The sum of bytes transferred on the wire */
>       uint64_t total_transferred;
>   
> @@ -303,7 +292,7 @@ void qemu_fflush(QEMUFile *f)
>               qemu_file_set_error_obj(f, -EIO, local_error);
>           } else {
>               uint64_t size = iov_size(f->iov, f->iovcnt);
> -            qemu_file_acct_rate_limit(f, size);
> +            migration_rate_account(size);
>               f->total_transferred += size;
>           }
>   
> @@ -356,7 +345,7 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
>           int ret = f->hooks->save_page(f, block_offset,
>                                         offset, size, bytes_sent);
>           if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
> -            qemu_file_acct_rate_limit(f, size);
> +            migration_rate_account(size);
>           }
>   
>           if (ret != RAM_SAVE_CONTROL_DELAYED &&
> @@ -727,43 +716,6 @@ uint64_t qemu_file_transferred(QEMUFile *f)
>       return f->total_transferred;
>   }
>   
> -int qemu_file_rate_limit(QEMUFile *f)
> -{
> -    if (qemu_file_get_error(f)) {
> -        return 1;
> -    }
> -    if (f->rate_limit_max == RATE_LIMIT_MAX) {
> -        return 0;
> -    }
> -    if (f->rate_limit_used > f->rate_limit_max) {
> -        return 1;
> -    }
> -    return 0;
> -}
> -
> -uint64_t qemu_file_get_rate_limit(QEMUFile *f)
> -{
> -    return f->rate_limit_max;
> -}
> -
> -void qemu_file_set_rate_limit(QEMUFile *f, uint64_t limit)
> -{
> -    /*
> -     * 'limit' is per second.  But we check it each 100 miliseconds.
> -     */
> -    f->rate_limit_max = limit / XFER_LIMIT_RATIO;
> -}
> -
> -void qemu_file_reset_rate_limit(QEMUFile *f)
> -{
> -    f->rate_limit_used = 0;
> -}
> -
> -void qemu_file_acct_rate_limit(QEMUFile *f, uint64_t len)
> -{
> -    f->rate_limit_used += len;
> -}
> -
>   void qemu_put_be16(QEMUFile *f, unsigned int v)
>   {
>       qemu_put_byte(f, v >> 8);
> diff --git a/migration/ram.c b/migration/ram.c
> index fd5a8db0f8..a706edecc0 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3126,7 +3126,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>   
>           t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
>           i = 0;
> -        while ((ret = qemu_file_rate_limit(f)) == 0 ||
> +        while ((ret = migration_rate_exceeded(f)) == 0 ||
>                  postcopy_has_request(rs)) {
>               int pages;
>   
> diff --git a/migration/savevm.c b/migration/savevm.c
> index c7af9050c2..6b783d9c39 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1345,7 +1345,7 @@ int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy)
>               !(se->ops->has_postcopy && se->ops->has_postcopy(se->opaque))) {
>               continue;
>           }
> -        if (qemu_file_rate_limit(f)) {
> +        if (migration_rate_exceeded(f)) {
>               return 0;
>           }
>           trace_savevm_section_start(se->idstr, se->section_id);