[Qemu-devel] [PATCH 0/2] optimize waiting for free thread to do compression

[Qemu-devel] [PATCH 0/2] optimize waiting for free thread to do compression

[guangrong.xiao]

From: Xiao Guangrong <xiaoguangrong@tencent.com>

Currently we have two behaviors if all threads are busy to do compression,
the main thread mush wait one of them becoming free if @compress-wait-thread
set to on or the main thread can directly return without wait and post
the page out as normal one

Both of them have its profits and short-comes, however, if the bandwidth is
not limited extremely so that compression can not use out all of it bandwidth,
at the same time, the migration process is easily throttled if we posted too
may pages as normal pages. None of them can work properly under this case

In order to use the bandwidth more effectively, we introduce the third
behavior, compress-wait-thread-adaptive, which make the main thread wait
if there is no bandwidth left or let the page go out as normal page if there
has enough bandwidth to make sure the migration process will not be
throttled

Another patch introduces a new statistic, pages-per-second, as bandwidth
or mbps is not enough to measure the performance of posting pages out as
we have compression, xbzrle, which can significantly reduce the amount of
the data size, instead, pages-per-second if the one we want

Performance data
================
We have limited the bandwidth to 300

                                Used Bandwidth     Pages-per-Second
compress-wait-thread = on         951.66 mbps         131784

compress-wait-thread = off        2491.74 mbps        93495
compress-wait-thread-adaptive     1982.94 mbps        162529
   = on

Xiao Guangrong (2):
  migration: introduce compress-wait-thread-adaptive
  migration: introduce pages-per-second

 hmp.c                 |  13 ++++++
 migration/migration.c |  49 +++++++++++++++++++-
 migration/migration.h |  12 +++++
 migration/ram.c       | 124 ++++++++++++++++++++++++++++++++++++++++++++++----
 qapi/migration.json   |  31 +++++++++++--
 5 files changed, 215 insertions(+), 14 deletions(-)

-- 
2.14.5

[Qemu-devel] [PATCH 1/2] migration: introduce compress-wait-thread-adaptive

[guangrong.xiao]

From: Xiao Guangrong <xiaoguangrong@tencent.com>

Currently we have two behaviors if all threads are busy to do compression,
the main thread mush wait one of them becoming free if @compress-wait-thread
set to on or the main thread can directly return without wait and post
the page out as normal one

Both of them have its profits and short-comes, however, if the bandwidth is
not limited extremely so that compression can not use out all of it bandwidth,
at the same time, the migration process is easily throttled if we posted too
may pages as normal pages. None of them can work properly under this case

In order to use the bandwidth more effectively, we introduce the third
behavior, compress-wait-thread-adaptive, which make the main thread wait
if there is no bandwidth left or let the page go out as normal page if there
has enough bandwidth to make sure the migration process will not be
throttled

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
---
 hmp.c                 |  11 +++++
 migration/migration.c |  37 ++++++++++++++++
 migration/migration.h |   4 ++
 migration/ram.c       | 118 +++++++++++++++++++++++++++++++++++++++++++++-----
 qapi/migration.json   |  26 ++++++++++-
 5 files changed, 184 insertions(+), 12 deletions(-)

diff --git a/hmp.c b/hmp.c
index 43ae9ec61a..2c5bb504d4 100644
--- a/hmp.c
+++ b/hmp.c
@@ -282,6 +282,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->compression->compressed_size);
         monitor_printf(mon, "compression rate: %0.2f\n",
                        info->compression->compression_rate);
+        monitor_printf(mon, "compress-no-wait-weight: %"PRIu64"\n",
+                       info->compression->compress_no_wait_weight);
     }
 
     if (info->has_cpu_throttle_percentage) {
@@ -344,6 +346,11 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
         monitor_printf(mon, "%s: %s\n",
             MigrationParameter_str(MIGRATION_PARAMETER_COMPRESS_WAIT_THREAD),
             params->compress_wait_thread ? "on" : "off");
+        assert(params->has_compress_wait_thread_adaptive);
+        monitor_printf(mon, "%s: %s\n",
+            MigrationParameter_str(
+                MIGRATION_PARAMETER_COMPRESS_WAIT_THREAD_ADAPTIVE),
+            params->compress_wait_thread_adaptive ? "on" : "off");
         assert(params->has_decompress_threads);
         monitor_printf(mon, "%s: %u\n",
             MigrationParameter_str(MIGRATION_PARAMETER_DECOMPRESS_THREADS),
@@ -1676,6 +1683,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
         p->has_compress_wait_thread = true;
         visit_type_bool(v, param, &p->compress_wait_thread, &err);
         break;
+    case MIGRATION_PARAMETER_COMPRESS_WAIT_THREAD_ADAPTIVE:
+        p->has_compress_wait_thread_adaptive = true;
+        visit_type_bool(v, param, &p->compress_wait_thread_adaptive, &err);
+        break;
     case MIGRATION_PARAMETER_DECOMPRESS_THREADS:
         p->has_decompress_threads = true;
         visit_type_int(v, param, &p->decompress_threads, &err);
diff --git a/migration/migration.c b/migration/migration.c
index 49ffb9997a..d19935b529 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -706,6 +706,9 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     params->compress_threads = s->parameters.compress_threads;
     params->has_compress_wait_thread = true;
     params->compress_wait_thread = s->parameters.compress_wait_thread;
+    params->has_compress_wait_thread_adaptive = true;
+    params->compress_wait_thread_adaptive =
+                            s->parameters.compress_wait_thread_adaptive;
     params->has_decompress_threads = true;
     params->decompress_threads = s->parameters.decompress_threads;
     params->has_cpu_throttle_initial = true;
@@ -799,6 +802,8 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
                                     compression_counters.compressed_size;
         info->compression->compression_rate =
                                     compression_counters.compression_rate;
+        info->compression->compress_no_wait_weight =
+                                compression_counters.compress_no_wait_weight;
     }
 
     if (cpu_throttle_active()) {
@@ -1132,6 +1137,11 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
         dest->compress_wait_thread = params->compress_wait_thread;
     }
 
+    if (params->has_compress_wait_thread_adaptive) {
+        dest->compress_wait_thread_adaptive =
+            params->compress_wait_thread_adaptive;
+    }
+
     if (params->has_decompress_threads) {
         dest->decompress_threads = params->decompress_threads;
     }
@@ -1204,6 +1214,11 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
         s->parameters.compress_wait_thread = params->compress_wait_thread;
     }
 
+    if (params->has_compress_wait_thread_adaptive) {
+        s->parameters.compress_wait_thread_adaptive =
+            params->compress_wait_thread_adaptive;
+    }
+
     if (params->has_decompress_threads) {
         s->parameters.decompress_threads = params->decompress_threads;
     }
@@ -1925,6 +1940,15 @@ bool migrate_postcopy_blocktime(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
 }
 
+int64_t migration_max_bandwidth(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->parameters.max_bandwidth;
+}
+
 bool migrate_use_compression(void)
 {
     MigrationState *s;
@@ -1961,6 +1985,15 @@ int migrate_compress_wait_thread(void)
     return s->parameters.compress_wait_thread;
 }
 
+int migrate_compress_wait_thread_adaptive(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->parameters.compress_wait_thread_adaptive;
+}
+
 int migrate_decompress_threads(void)
 {
     MigrationState *s;
@@ -2898,6 +2931,8 @@ static void migration_update_counters(MigrationState *s,
     s->mbps = (((double) transferred * 8.0) /
                ((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
 
+    compress_adaptive_update(s->mbps);
+
     /*
      * if we haven't sent anything, we don't want to
      * recalculate. 10000 is a small enough number for our purposes
@@ -3232,6 +3267,8 @@ static Property migration_properties[] = {
                       DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT),
     DEFINE_PROP_BOOL("x-compress-wait-thread", MigrationState,
                       parameters.compress_wait_thread, true),
+    DEFINE_PROP_BOOL("x-ccompress-wait-thread-adaptive", MigrationState,
+                      parameters.compress_wait_thread_adaptive, false),
     DEFINE_PROP_UINT8("x-decompress-threads", MigrationState,
                       parameters.decompress_threads,
                       DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT),
diff --git a/migration/migration.h b/migration/migration.h
index e413d4d8b6..d631776230 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -270,11 +270,15 @@ bool migrate_use_block(void);
 bool migrate_use_block_incremental(void);
 int migrate_max_cpu_throttle(void);
 bool migrate_use_return_path(void);
+int64_t migration_max_bandwidth(void);
 
 bool migrate_use_compression(void);
 int migrate_compress_level(void);
 int migrate_compress_threads(void);
 int migrate_compress_wait_thread(void);
+int migrate_compress_wait_thread_adaptive(void);
+void compress_adaptive_update(double mbps);
+
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
 bool migrate_postcopy_blocktime(void);
diff --git a/migration/ram.c b/migration/ram.c
index 7e7deec4d8..3b08a605e4 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -276,6 +276,8 @@ struct RAMSrcPageRequest {
     QSIMPLEQ_ENTRY(RAMSrcPageRequest) next_req;
 };
 
+#define COMPRESS_BUSY_COUNT_PERIOD 100
+
 /* State of RAM for migration */
 struct RAMState {
     /* QEMUFile used for this migration */
@@ -292,6 +294,19 @@ struct RAMState {
     bool ram_bulk_stage;
     /* How many times we have dirty too many pages */
     int dirty_rate_high_cnt;
+
+    /* used by by compress-wait-thread-adaptive */
+    /*
+     * the count for the case that all compress threads are busy to
+     * handle a page in a period
+     */
+    uint8_t compress_busy_count;
+    /*
+     * the number of pages that can be directly posted as normal page when
+     * all compress threads are busy in a period
+     */
+    uint8_t compress_no_wait_left;
+
     /* these variables are used for bitmap sync */
     /* last time we did a full bitmap_sync */
     int64_t time_last_bitmap_sync;
@@ -470,6 +485,8 @@ static void compress_threads_save_cleanup(void)
     comp_param = NULL;
 }
 
+static void compress_adaptive_init(void);
+
 static int compress_threads_save_setup(void)
 {
     int i, thread_count;
@@ -477,6 +494,9 @@ static int compress_threads_save_setup(void)
     if (!migrate_use_compression()) {
         return 0;
     }
+
+    compress_adaptive_init();
+
     thread_count = migrate_compress_threads();
     compress_threads = g_new0(QemuThread, thread_count);
     comp_param = g_new0(CompressParam, thread_count);
@@ -1593,6 +1613,67 @@ uint64_t ram_pagesize_summary(void)
     return summary;
 }
 
+static void compress_adaptive_init(void)
+{
+    /* fully wait on default. */
+     compression_counters.compress_no_wait_weight = 0;
+     ram_state->compress_no_wait_left = 0;
+     ram_state->compress_busy_count = 0;
+}
+
+void compress_adaptive_update(double mbps)
+{
+    int64_t rate_limit, remain_bw, max_bw = migration_max_bandwidth();
+
+    if (!migrate_use_compression() ||
+        !migrate_compress_wait_thread_adaptive()) {
+        return;
+    }
+
+    /* no bandwith is set to the file then we can not do adaptive adjustment */
+    rate_limit = qemu_file_get_rate_limit(migrate_get_current()->to_dst_file);
+    if (rate_limit == 0 || rate_limit == INT64_MAX) {
+        return;
+    }
+
+    max_bw = (max_bw >> 20) * 8;
+    remain_bw = abs(max_bw - (int64_t)(mbps));
+    if (remain_bw <= ((max_bw / 10) * 2)) {
+        /* if we have used all the bandwidth, let's compress more. */
+        if (compression_counters.compress_no_wait_weight) {
+            compression_counters.compress_no_wait_weight--;
+        }
+        goto exit;
+    }
+
+    /* have enough bandwidth left, do not need to compress so aggressively */
+    if (compression_counters.compress_no_wait_weight !=
+        COMPRESS_BUSY_COUNT_PERIOD) {
+        compression_counters.compress_no_wait_weight++;
+    }
+
+exit:
+    ram_state->compress_busy_count = 0;
+    ram_state->compress_no_wait_left =
+                            compression_counters.compress_no_wait_weight;
+}
+
+static bool compress_adaptive_need_wait(void)
+{
+    if (++ram_state->compress_busy_count == COMPRESS_BUSY_COUNT_PERIOD) {
+        ram_state->compress_busy_count = 0;
+        ram_state->compress_no_wait_left =
+                    compression_counters.compress_no_wait_weight;
+    }
+
+    if (ram_state->compress_no_wait_left) {
+        ram_state->compress_no_wait_left--;
+        return false;
+    }
+
+    return true;
+}
+
 static void migration_update_rates(RAMState *rs, int64_t end_time)
 {
     uint64_t page_count = rs->target_page_count - rs->target_page_count_prev;
@@ -1970,6 +2051,15 @@ static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block,
 {
     int idx, thread_count, bytes_xmit = -1, pages = -1;
     bool wait = migrate_compress_wait_thread();
+    bool adaptive = migrate_compress_wait_thread_adaptive();
+
+    /*
+     * 'compress-wait-thread-adaptive' has higher priority than
+     * 'compress-wait-thread'.
+     */
+    if (adaptive) {
+        wait = false;
+    }
 
     thread_count = migrate_compress_threads();
     qemu_mutex_lock(&comp_done_lock);
@@ -1984,20 +2074,29 @@ retry:
             qemu_mutex_unlock(&comp_param[idx].mutex);
             pages = 1;
             update_compress_thread_counts(&comp_param[idx], bytes_xmit);
-            break;
+            goto exit;
         }
     }
 
+    if (adaptive && !wait) {
+        /* it is the first time go to the loop */
+        wait = compress_adaptive_need_wait();
+    }
+
     /*
-     * wait for the free thread if the user specifies 'compress-wait-thread',
-     * otherwise we will post the page out in the main thread as normal page.
+     * wait for the free thread if the user specifies
+     * 'compress-wait-thread-adaptive' that detected the bandwidth is
+     * not enough or compress-wait-thread', otherwise we will post the
+     * page out in the main thread as normal page.
      */
-    if (pages < 0 && wait) {
+    if (wait) {
         qemu_cond_wait(&comp_done_cond, &comp_done_lock);
         goto retry;
     }
-    qemu_mutex_unlock(&comp_done_lock);
 
+
+exit:
+    qemu_mutex_unlock(&comp_done_lock);
     return pages;
 }
 
@@ -3147,19 +3246,18 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     RAMState **rsp = opaque;
     RAMBlock *block;
 
-    if (compress_threads_save_setup()) {
-        return -1;
-    }
-
     /* migration has already setup the bitmap, reuse it. */
     if (!migration_in_colo_state()) {
         if (ram_init_all(rsp) != 0) {
-            compress_threads_save_cleanup();
             return -1;
         }
     }
     (*rsp)->f = f;
 
+    if (compress_threads_save_setup()) {
+        return -1;
+    }
+
     rcu_read_lock();
 
     qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
diff --git a/qapi/migration.json b/qapi/migration.json
index 38d4c41d88..6d925c73fc 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -90,11 +90,16 @@
 #
 # @compression-rate: rate of compressed size
 #
+# @compress-no-wait-weight: it controls how many pages are directly posted
+#     out as normal page when all compression threads are currently busy.
+#     Only available if compress-wait-thread-adaptive is on. (Since 3.2)
+#
 # Since: 3.1
 ##
 { 'struct': 'CompressionStats',
   'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
-	   'compressed-size': 'int', 'compression-rate': 'number' } }
+	   'compressed-size': 'int', 'compression-rate': 'number',
+	   'compress-no-wait-weight': 'int'} }
 
 ##
 # @MigrationStatus:
@@ -490,6 +495,11 @@
 #                        compression thread to become available; otherwise,
 #                        send the page uncompressed. (Since 3.1)
 #
+# @compress-wait-thread-adaptive: Adaptively controls compress-wait-thread
+#          based on the rate limit and it's off on default. When it is on
+#          and it has enough bandwidth, it acts as compress-wait-thread is
+#          off. (Since 3.2)
+#
 # @decompress-threads: Set decompression thread count to be used in live
 #          migration, the decompression thread count is an integer between 1
 #          and 255. Usually, decompression is at least 4 times as fast as
@@ -558,7 +568,7 @@
 ##
 { 'enum': 'MigrationParameter',
   'data': ['compress-level', 'compress-threads', 'decompress-threads',
-           'compress-wait-thread',
+           'compress-wait-thread', 'compress-wait-thread-adaptive',
            'cpu-throttle-initial', 'cpu-throttle-increment',
            'tls-creds', 'tls-hostname', 'max-bandwidth',
            'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
@@ -578,6 +588,11 @@
 #                        compression thread to become available; otherwise,
 #                        send the page uncompressed. (Since 3.1)
 #
+# @compress-wait-thread-adaptive: Adaptively controls compress-wait-thread
+#          based on the rate limit and it's off on default. When it is on
+#          and it has enough bandwidth, it acts as compress-wait-thread is
+#          off. (Since 3.2)
+#
 # @decompress-threads: decompression thread count
 #
 # @cpu-throttle-initial: Initial percentage of time guest cpus are
@@ -653,6 +668,7 @@
   'data': { '*compress-level': 'int',
             '*compress-threads': 'int',
             '*compress-wait-thread': 'bool',
+            '*compress-wait-thread-adaptive': 'bool',
             '*decompress-threads': 'int',
             '*cpu-throttle-initial': 'int',
             '*cpu-throttle-increment': 'int',
@@ -698,6 +714,11 @@
 #                        compression thread to become available; otherwise,
 #                        send the page uncompressed. (Since 3.1)
 #
+# @compress-wait-thread-adaptive: Adaptively controls compress-wait-thread
+#          based on the rate limit and it's off on default. When it is on
+#          and it has enough bandwidth, it acts as compress-wait-thread is
+#          off. (Since 3.2)
+#
 # @decompress-threads: decompression thread count
 #
 # @cpu-throttle-initial: Initial percentage of time guest cpus are
@@ -769,6 +790,7 @@
   'data': { '*compress-level': 'uint8',
             '*compress-threads': 'uint8',
             '*compress-wait-thread': 'bool',
+            '*compress-wait-thread-adaptive': 'bool',
             '*decompress-threads': 'uint8',
             '*cpu-throttle-initial': 'uint8',
             '*cpu-throttle-increment': 'uint8',
-- 
2.14.5

[Qemu-devel] [PATCH 2/2] migration: introduce pages-per-second

[guangrong.xiao]

From: Xiao Guangrong <xiaoguangrong@tencent.com>

It introduces a new statistic, pages-per-second, as bandwidth or mbps is
not enough to measure the performance of posting pages out as we have
compression, xbzrle, which can significantly reduce the amount of the
data size, instead, pages-per-second if the one we want

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
---
 hmp.c                 |  2 ++
 migration/migration.c | 12 +++++++++++-
 migration/migration.h |  8 ++++++++
 migration/ram.c       |  6 ++++++
 qapi/migration.json   |  5 ++++-
 5 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/hmp.c b/hmp.c
index 2c5bb504d4..bd7e30cc2e 100644
--- a/hmp.c
+++ b/hmp.c
@@ -236,6 +236,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->ram->page_size >> 10);
         monitor_printf(mon, "multifd bytes: %" PRIu64 " kbytes\n",
                        info->ram->multifd_bytes >> 10);
+        monitor_printf(mon, "pages-per-second: %" PRIu64 "\n",
+                       info->ram->pages_per_second);
 
         if (info->ram->dirty_pages_rate) {
             monitor_printf(mon, "dirty pages rate: %" PRIu64 " pages\n",
diff --git a/migration/migration.c b/migration/migration.c
index d19935b529..2a54cd3423 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -780,6 +780,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
     info->ram->postcopy_requests = ram_counters.postcopy_requests;
     info->ram->page_size = qemu_target_page_size();
     info->ram->multifd_bytes = ram_counters.multifd_bytes;
+    info->ram->pages_per_second = s->pages_per_second;
 
     if (migrate_use_xbzrle()) {
         info->has_xbzrle_cache = true;
@@ -1578,6 +1579,7 @@ void migrate_init(MigrationState *s)
     s->rp_state.from_dst_file = NULL;
     s->rp_state.error = false;
     s->mbps = 0.0;
+    s->pages_per_second = 0.0;
     s->downtime = 0;
     s->expected_downtime = 0;
     s->setup_time = 0;
@@ -2914,7 +2916,7 @@ static void migration_calculate_complete(MigrationState *s)
 static void migration_update_counters(MigrationState *s,
                                       int64_t current_time)
 {
-    uint64_t transferred, time_spent;
+    uint64_t transferred, transferred_pages, time_spent;
     uint64_t current_bytes; /* bytes transferred since the beginning */
     double bandwidth;
 
@@ -2931,6 +2933,12 @@ static void migration_update_counters(MigrationState *s,
     s->mbps = (((double) transferred * 8.0) /
                ((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
 
+
+    transferred_pages = ram_get_total_transferred_pages() -
+                            s->iteration_initial_pages;
+    s->pages_per_second = (double) transferred_pages /
+                             (((double) time_spent / 1000.0));
+
     compress_adaptive_update(s->mbps);
 
     /*
@@ -2945,6 +2953,7 @@ static void migration_update_counters(MigrationState *s,
 
     s->iteration_start_time = current_time;
     s->iteration_initial_bytes = current_bytes;
+    s->iteration_initial_pages = ram_get_total_transferred_pages();
 
     trace_migrate_transferred(transferred, time_spent,
                               bandwidth, s->threshold_size);
@@ -3351,6 +3360,7 @@ static void migration_instance_init(Object *obj)
 
     ms->state = MIGRATION_STATUS_NONE;
     ms->mbps = -1;
+    ms->pages_per_second = -1;
     qemu_sem_init(&ms->pause_sem, 0);
     qemu_mutex_init(&ms->error_mutex);
 
diff --git a/migration/migration.h b/migration/migration.h
index d631776230..73a6803cc4 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -126,6 +126,12 @@ struct MigrationState
      */
     QemuSemaphore rate_limit_sem;
 
+    /* pages already send at the beggining of current interation */
+    uint64_t iteration_initial_pages;
+
+    /* pages transferred per second */
+    double pages_per_second;
+
     /* bytes already send at the beggining of current interation */
     uint64_t iteration_initial_bytes;
     /* time at the start of current iteration */
@@ -279,6 +285,8 @@ int migrate_compress_wait_thread(void);
 int migrate_compress_wait_thread_adaptive(void);
 void compress_adaptive_update(double mbps);
 
+uint64_t ram_get_total_transferred_pages(void);
+
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
 bool migrate_postcopy_blocktime(void);
diff --git a/migration/ram.c b/migration/ram.c
index 3b08a605e4..b6b08a4800 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1613,6 +1613,12 @@ uint64_t ram_pagesize_summary(void)
     return summary;
 }
 
+uint64_t ram_get_total_transferred_pages(void)
+{
+    return  ram_counters.normal + ram_counters.duplicate +
+                compression_counters.pages + xbzrle_counters.pages;
+}
+
 static void compress_adaptive_init(void)
 {
     /* fully wait on default. */
diff --git a/qapi/migration.json b/qapi/migration.json
index 6d925c73fc..e64b2e3901 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -41,6 +41,9 @@
 #
 # @multifd-bytes: The number of bytes sent through multifd (since 3.0)
 #
+# @pages-per-second: the number of memory pages transferred per second
+#        (Since 3.2)
+#
 # Since: 0.14.0
 ##
 { 'struct': 'MigrationStats',
@@ -49,7 +52,7 @@
            'normal-bytes': 'int', 'dirty-pages-rate' : 'int',
            'mbps' : 'number', 'dirty-sync-count' : 'int',
            'postcopy-requests' : 'int', 'page-size' : 'int',
-           'multifd-bytes' : 'uint64' } }
+           'multifd-bytes' : 'uint64', 'pages-per-second' : 'uint64' } }
 
 ##
 # @XBZRLECacheStats:
-- 
2.14.5

Re: [Qemu-devel] [PATCH 0/2] optimize waiting for free thread to do compression

[Peter Xu]

On Thu, Dec 13, 2018 at 03:57:25PM +0800, guangrong.xiao@gmail.com wrote:
> From: Xiao Guangrong <xiaoguangrong@tencent.com>
> 
> Currently we have two behaviors if all threads are busy to do compression,
> the main thread mush wait one of them becoming free if @compress-wait-thread
> set to on or the main thread can directly return without wait and post
> the page out as normal one
> 
> Both of them have its profits and short-comes, however, if the bandwidth is
> not limited extremely so that compression can not use out all of it bandwidth,
> at the same time, the migration process is easily throttled if we posted too
> may pages as normal pages. None of them can work properly under this case
> 
> In order to use the bandwidth more effectively, we introduce the third
> behavior, compress-wait-thread-adaptive, which make the main thread wait
> if there is no bandwidth left or let the page go out as normal page if there
> has enough bandwidth to make sure the migration process will not be
> throttled
> 
> Another patch introduces a new statistic, pages-per-second, as bandwidth
> or mbps is not enough to measure the performance of posting pages out as
> we have compression, xbzrle, which can significantly reduce the amount of
> the data size, instead, pages-per-second if the one we want
> 
> Performance data
> ================
> We have limited the bandwidth to 300
> 
>                                 Used Bandwidth     Pages-per-Second
> compress-wait-thread = on         951.66 mbps         131784
> 
> compress-wait-thread = off        2491.74 mbps        93495
> compress-wait-thread-adaptive     1982.94 mbps        162529
>    = on

Sounds reasonable to me, though it looks like there're only three
options: on, off, adaptive.  Should we squash the two parameters?

Thanks,

-- 
Peter Xu

Re: [Qemu-devel] [PATCH 0/2] optimize waiting for free thread to do compression(Internet mail)

[xiaoguangrong(Xiao Guangrong)]

On 12/21/18 4:11 PM, Peter Xu wrote:
> On Thu, Dec 13, 2018 at 03:57:25PM +0800, guangrong.xiao@gmail.com wrote:
>> From: Xiao Guangrong <xiaoguangrong@tencent.com>
>>
>> Currently we have two behaviors if all threads are busy to do compression,
>> the main thread mush wait one of them becoming free if @compress-wait-thread
>> set to on or the main thread can directly return without wait and post
>> the page out as normal one
>>
>> Both of them have its profits and short-comes, however, if the bandwidth is
>> not limited extremely so that compression can not use out all of it bandwidth,
>> at the same time, the migration process is easily throttled if we posted too
>> may pages as normal pages. None of them can work properly under this case
>>
>> In order to use the bandwidth more effectively, we introduce the third
>> behavior, compress-wait-thread-adaptive, which make the main thread wait
>> if there is no bandwidth left or let the page go out as normal page if there
>> has enough bandwidth to make sure the migration process will not be
>> throttled
>>
>> Another patch introduces a new statistic, pages-per-second, as bandwidth
>> or mbps is not enough to measure the performance of posting pages out as
>> we have compression, xbzrle, which can significantly reduce the amount of
>> the data size, instead, pages-per-second if the one we want
>>
>> Performance data
>> ================
>> We have limited the bandwidth to 300
>>
>>                                  Used Bandwidth     Pages-per-Second
>> compress-wait-thread = on         951.66 mbps         131784
>>
>> compress-wait-thread = off        2491.74 mbps        93495
>> compress-wait-thread-adaptive     1982.94 mbps        162529
>>     = on
> 
> Sounds reasonable to me, though it looks like there're only three
> options: on, off, adaptive.  Should we squash the two parameters?

Thanks for your review, Peter!

That's good to me, if other guys do not have objects, i will do it in the
next version.