diff mbox

[05/12] migration: show the statistics of compression

Message ID 20180604095520.8563-6-xiaoguangrong@tencent.com (mailing list archive)
State New, archived
Headers show

Commit Message

Xiao Guangrong June 4, 2018, 9:55 a.m. UTC
From: Xiao Guangrong <xiaoguangrong@tencent.com>

Then the uses can adjust the parameters based on this info

Currently, it includes:
pages: amount of pages compressed and transferred to the target VM
busy: amount of count that no free thread to compress data
busy-rate: rate of thread busy
reduced-size: amount of bytes reduced by compression
compression-rate: rate of compressed size

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
---
 hmp.c                 | 13 +++++++++++++
 migration/migration.c | 11 +++++++++++
 migration/ram.c       | 37 +++++++++++++++++++++++++++++++++++++
 migration/ram.h       |  1 +
 qapi/migration.json   | 25 ++++++++++++++++++++++++-
 5 files changed, 86 insertions(+), 1 deletion(-)

Comments

Eric Blake June 4, 2018, 10:31 p.m. UTC | #1
On 06/04/2018 04:55 AM, guangrong.xiao@gmail.com wrote:
> From: Xiao Guangrong <xiaoguangrong@tencent.com>
> 
> Then the uses can adjust the parameters based on this info
> 
> Currently, it includes:
> pages: amount of pages compressed and transferred to the target VM
> busy: amount of count that no free thread to compress data
> busy-rate: rate of thread busy
> reduced-size: amount of bytes reduced by compression
> compression-rate: rate of compressed size
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
> ---

> +++ b/qapi/migration.json
> @@ -72,6 +72,26 @@
>              'cache-miss': 'int', 'cache-miss-rate': 'number',
>              'overflow': 'int' } }
>   
> +##
> +# @CompressionStats:
> +#
> +# Detailed compression migration statistics

Sounds better as s/compression migration/migration compression/

> +#
> +# @pages: amount of pages compressed and transferred to the target VM
> +#
> +# @busy: amount of count that no free thread to compress data

Not sure what was meant, maybe:

@busy: count of times that no free thread was available to compress data

> +#
> +# @busy-rate: rate of thread busy

In what unit? pages per second?

> +#
> +# @reduced-size: amount of bytes reduced by compression
> +#
> +# @compression-rate: rate of compressed size

In what unit?

> +#
> +##

Missing a 'Since: 3.0' tag

> +{ 'struct': 'CompressionStats',
> +  'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
> +	   'reduced-size': 'int', 'compression-rate': 'number' } }
> +
>   ##
>   # @MigrationStatus:
>   #
> @@ -169,6 +189,8 @@
>   #           only present when the postcopy-blocktime migration capability
>   #           is enabled. (Since 2.13)

Pre-existing - we need to fix this 2.13 to be 3.0 (if it isn't already 
fixed)

>   #
> +# @compression: compression migration statistics, only returned if compression
> +#           feature is on and status is 'active' or 'completed' (Since 2.14)

There will not be a 2.14 (for that matter, not even a 2.13).  The next 
release is 3.0.

>   #
>   # Since: 0.14.0
>   ##
> @@ -183,7 +205,8 @@
>              '*cpu-throttle-percentage': 'int',
>              '*error-desc': 'str',
>              '*postcopy-blocktime' : 'uint32',
> -           '*postcopy-vcpu-blocktime': ['uint32']} }
> +           '*postcopy-vcpu-blocktime': ['uint32'],
> +           '*compression': 'CompressionStats'} }
>   
>   ##
>   # @query-migrate:
>
Xiao Guangrong June 6, 2018, 12:44 p.m. UTC | #2
On 06/05/2018 06:31 AM, Eric Blake wrote:
> On 06/04/2018 04:55 AM, guangrong.xiao@gmail.com wrote:
>> From: Xiao Guangrong <xiaoguangrong@tencent.com>
>>
>> Then the uses can adjust the parameters based on this info
>>
>> Currently, it includes:
>> pages: amount of pages compressed and transferred to the target VM
>> busy: amount of count that no free thread to compress data
>> busy-rate: rate of thread busy
>> reduced-size: amount of bytes reduced by compression
>> compression-rate: rate of compressed size
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
>> ---
> 
>> +++ b/qapi/migration.json
>> @@ -72,6 +72,26 @@
>>              'cache-miss': 'int', 'cache-miss-rate': 'number',
>>              'overflow': 'int' } }
>> +##
>> +# @CompressionStats:
>> +#
>> +# Detailed compression migration statistics
> 
> Sounds better as s/compression migration/migration compression/

Indeed.

> 
>> +#
>> +# @pages: amount of pages compressed and transferred to the target VM
>> +#
>> +# @busy: amount of count that no free thread to compress data
> 
> Not sure what was meant, maybe:
> 
> @busy: count of times that no free thread was available to compress data
> 

Yup, that's better.

>> +#
>> +# @busy-rate: rate of thread busy
> 
> In what unit? pages per second?

It's calculated by:
    pages-directly-posted-out-without-compression / total-page-posted-out

> 
>> +#
>> +# @reduced-size: amount of bytes reduced by compression
>> +#
>> +# @compression-rate: rate of compressed size
> 
> In what unit?
> 

It's calculated by:
    size-posted-out-after-compression / (compressed-page * page_size, i.e, that is
the raw data without compression)

>> +#
>> +##
> 
> Missing a 'Since: 3.0' tag
> 

Wow, directly upgrade to 3.0, big step. :-)
Will add this tag in the next version.

>> +{ 'struct': 'CompressionStats',
>> +  'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
>> +       'reduced-size': 'int', 'compression-rate': 'number' } }
>> +
>>   ##
>>   # @MigrationStatus:
>>   #
>> @@ -169,6 +189,8 @@
>>   #           only present when the postcopy-blocktime migration capability
>>   #           is enabled. (Since 2.13)
> 
> Pre-existing - we need to fix this 2.13 to be 3.0 (if it isn't already fixed)

I should re-sync the repo before making patches next time.

> 
>>   #
>> +# @compression: compression migration statistics, only returned if compression
>> +#           feature is on and status is 'active' or 'completed' (Since 2.14)
> 
> There will not be a 2.14 (for that matter, not even a 2.13).  The next release is 3.0.

Okay, will fix.
Dr. David Alan Gilbert June 13, 2018, 4:25 p.m. UTC | #3
* guangrong.xiao@gmail.com (guangrong.xiao@gmail.com) wrote:
> From: Xiao Guangrong <xiaoguangrong@tencent.com>
> 
> Then the uses can adjust the parameters based on this info
> 
> Currently, it includes:
> pages: amount of pages compressed and transferred to the target VM
> busy: amount of count that no free thread to compress data
> busy-rate: rate of thread busy
> reduced-size: amount of bytes reduced by compression
> compression-rate: rate of compressed size
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
> ---
>  hmp.c                 | 13 +++++++++++++
>  migration/migration.c | 11 +++++++++++
>  migration/ram.c       | 37 +++++++++++++++++++++++++++++++++++++
>  migration/ram.h       |  1 +
>  qapi/migration.json   | 25 ++++++++++++++++++++++++-
>  5 files changed, 86 insertions(+), 1 deletion(-)
> 
> diff --git a/hmp.c b/hmp.c
> index ef93f4878b..5c2d3bd318 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -269,6 +269,19 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
>                         info->xbzrle_cache->overflow);
>      }
>  
> +    if (info->has_compression) {
> +        monitor_printf(mon, "compression pages: %" PRIu64 " pages\n",
> +                       info->compression->pages);
> +        monitor_printf(mon, "compression busy: %" PRIu64 "\n",
> +                       info->compression->busy);
> +        monitor_printf(mon, "compression busy rate: %0.2f\n",
> +                       info->compression->busy_rate);
> +        monitor_printf(mon, "compression reduced size: %" PRIu64 "\n",
> +                       info->compression->reduced_size);
> +        monitor_printf(mon, "compression rate: %0.2f\n",
> +                       info->compression->compression_rate);
> +    }
> +
>      if (info->has_cpu_throttle_percentage) {
>          monitor_printf(mon, "cpu throttle percentage: %" PRIu64 "\n",
>                         info->cpu_throttle_percentage);
> diff --git a/migration/migration.c b/migration/migration.c
> index 05aec2c905..bf7c63a5a2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -693,6 +693,17 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
>          info->xbzrle_cache->overflow = xbzrle_counters.overflow;
>      }
>  
> +    if (migrate_use_compression()) {
> +        info->has_compression = true;
> +        info->compression = g_malloc0(sizeof(*info->compression));
> +        info->compression->pages = compression_counters.pages;
> +        info->compression->busy = compression_counters.busy;
> +        info->compression->busy_rate = compression_counters.busy_rate;
> +        info->compression->reduced_size = compression_counters.reduced_size;
> +        info->compression->compression_rate =
> +                                    compression_counters.compression_rate;
> +    }
> +
>      if (cpu_throttle_active()) {
>          info->has_cpu_throttle_percentage = true;
>          info->cpu_throttle_percentage = cpu_throttle_get_percentage();
> diff --git a/migration/ram.c b/migration/ram.c
> index ee03b28435..80914b747e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -292,6 +292,15 @@ struct RAMState {
>      uint64_t num_dirty_pages_period;
>      /* xbzrle misses since the beginning of the period */
>      uint64_t xbzrle_cache_miss_prev;
> +
> +    /* compression statistics since the beginning of the period */
> +    /* amount of count that no free thread to compress data */
> +    uint64_t compress_thread_busy_prev;
> +    /* amount bytes reduced by compression */
> +    uint64_t compress_reduced_size_prev;
> +    /* amount of compressed pages */
> +    uint64_t compress_pages_prev;
> +
>      /* number of iterations at the beginning of period */
>      uint64_t iterations_prev;
>      /* Iterations since start */
> @@ -329,6 +338,8 @@ struct PageSearchStatus {
>  };
>  typedef struct PageSearchStatus PageSearchStatus;
>  
> +CompressionStats compression_counters;
> +
>  struct CompressParam {
>      bool done;
>      bool quit;
> @@ -1147,6 +1158,24 @@ static void migration_update_rates(RAMState *rs, int64_t end_time)
>              rs->xbzrle_cache_miss_prev) / iter_count;
>          rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss;
>      }
> +
> +    if (migrate_use_compression()) {
> +        uint64_t comp_pages;
> +
> +        compression_counters.busy_rate = (double)(compression_counters.busy -
> +            rs->compress_thread_busy_prev) / iter_count;
> +        rs->compress_thread_busy_prev = compression_counters.busy;
> +
> +        comp_pages = compression_counters.pages - rs->compress_pages_prev;
> +        if (comp_pages) {
> +            compression_counters.compression_rate =
> +                (double)(compression_counters.reduced_size -
> +                rs->compress_reduced_size_prev) /
> +                (comp_pages * TARGET_PAGE_SIZE);
> +            rs->compress_pages_prev = compression_counters.pages;
> +            rs->compress_reduced_size_prev = compression_counters.reduced_size;
> +        }
> +    }
>  }
>  
>  static void migration_bitmap_sync(RAMState *rs)
> @@ -1412,6 +1441,9 @@ static void flush_compressed_data(RAMState *rs)
>          qemu_mutex_lock(&comp_param[idx].mutex);
>          if (!comp_param[idx].quit) {
>              len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
> +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
> +            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;

I think I'd rather save just len+8 rather than than the subtraction.

I think other than that, and Eric's comments, it's OK.

Dave

> +            compression_counters.pages++;
>              ram_counters.transferred += len;
>          }
>          qemu_mutex_unlock(&comp_param[idx].mutex);
> @@ -1441,6 +1473,10 @@ static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block,
>              qemu_cond_signal(&comp_param[idx].cond);
>              qemu_mutex_unlock(&comp_param[idx].mutex);
>              pages = 1;
> +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
> +            compression_counters.reduced_size += TARGET_PAGE_SIZE -
> +                                                 bytes_xmit + 8;
> +            compression_counters.pages++;
>              ram_counters.transferred += bytes_xmit;
>              break;
>          }
> @@ -1760,6 +1796,7 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
>          if (res > 0) {
>              return res;
>          }
> +        compression_counters.busy++;
>      }
>  
>      return ram_save_page(rs, pss, last_stage);
> diff --git a/migration/ram.h b/migration/ram.h
> index d386f4d641..7b009b23e5 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -36,6 +36,7 @@
>  
>  extern MigrationStats ram_counters;
>  extern XBZRLECacheStats xbzrle_counters;
> +extern CompressionStats compression_counters;
>  
>  int xbzrle_cache_resize(int64_t new_size, Error **errp);
>  uint64_t ram_bytes_remaining(void);
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 3ec418dabf..a11987cdc4 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -72,6 +72,26 @@
>             'cache-miss': 'int', 'cache-miss-rate': 'number',
>             'overflow': 'int' } }
>  
> +##
> +# @CompressionStats:
> +#
> +# Detailed compression migration statistics
> +#
> +# @pages: amount of pages compressed and transferred to the target VM
> +#
> +# @busy: amount of count that no free thread to compress data
> +#
> +# @busy-rate: rate of thread busy
> +#
> +# @reduced-size: amount of bytes reduced by compression
> +#
> +# @compression-rate: rate of compressed size
> +#
> +##
> +{ 'struct': 'CompressionStats',
> +  'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
> +	   'reduced-size': 'int', 'compression-rate': 'number' } }
> +
>  ##
>  # @MigrationStatus:
>  #
> @@ -169,6 +189,8 @@
>  #           only present when the postcopy-blocktime migration capability
>  #           is enabled. (Since 2.13)
>  #
> +# @compression: compression migration statistics, only returned if compression
> +#           feature is on and status is 'active' or 'completed' (Since 2.14)
>  #
>  # Since: 0.14.0
>  ##
> @@ -183,7 +205,8 @@
>             '*cpu-throttle-percentage': 'int',
>             '*error-desc': 'str',
>             '*postcopy-blocktime' : 'uint32',
> -           '*postcopy-vcpu-blocktime': ['uint32']} }
> +           '*postcopy-vcpu-blocktime': ['uint32'],
> +           '*compression': 'CompressionStats'} }
>  
>  ##
>  # @query-migrate:
> -- 
> 2.14.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Xiao Guangrong June 14, 2018, 6:48 a.m. UTC | #4
On 06/14/2018 12:25 AM, Dr. David Alan Gilbert wrote:
  }
>>   
>>   static void migration_bitmap_sync(RAMState *rs)
>> @@ -1412,6 +1441,9 @@ static void flush_compressed_data(RAMState *rs)
>>           qemu_mutex_lock(&comp_param[idx].mutex);
>>           if (!comp_param[idx].quit) {
>>               len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
>> +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
>> +            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;
> 
> I think I'd rather save just len+8 rather than than the subtraction.
>
Hmmmmmm, is this what you want?
       compression_counters.reduced_size += len - 8;

Then calculate the real reduced size in populate_ram_info() where we return this
info to the user:
       info->compression->reduced_size = compression_counters.pages * PAGE_SIZE - compression_counters.reduced_size;

Right?

> I think other than that, and Eric's comments, it's OK.
> 

Thanks.
Dr. David Alan Gilbert July 16, 2018, 7:01 p.m. UTC | #5
* Xiao Guangrong (guangrong.xiao@gmail.com) wrote:
> 
> 
> On 06/14/2018 12:25 AM, Dr. David Alan Gilbert wrote:
>  }
> > >   static void migration_bitmap_sync(RAMState *rs)
> > > @@ -1412,6 +1441,9 @@ static void flush_compressed_data(RAMState *rs)
> > >           qemu_mutex_lock(&comp_param[idx].mutex);
> > >           if (!comp_param[idx].quit) {
> > >               len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
> > > +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
> > > +            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;
> > 
> > I think I'd rather save just len+8 rather than than the subtraction.
> > 
> Hmmmmmm, is this what you want?
>       compression_counters.reduced_size += len - 8;
> 
> Then calculate the real reduced size in populate_ram_info() where we return this
> info to the user:
>       info->compression->reduced_size = compression_counters.pages * PAGE_SIZE - compression_counters.reduced_size;
> 
> Right?

I mean I'd rather see the actual size presented to the user rather than
the saving compared to uncompressed.

Dave

> > I think other than that, and Eric's comments, it's OK.
> > 
> 
> Thanks.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Xiao Guangrong July 18, 2018, 8:51 a.m. UTC | #6
On 07/17/2018 03:01 AM, Dr. David Alan Gilbert wrote:
> * Xiao Guangrong (guangrong.xiao@gmail.com) wrote:
>>
>>
>> On 06/14/2018 12:25 AM, Dr. David Alan Gilbert wrote:
>>   }
>>>>    static void migration_bitmap_sync(RAMState *rs)
>>>> @@ -1412,6 +1441,9 @@ static void flush_compressed_data(RAMState *rs)
>>>>            qemu_mutex_lock(&comp_param[idx].mutex);
>>>>            if (!comp_param[idx].quit) {
>>>>                len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
>>>> +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
>>>> +            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;
>>>
>>> I think I'd rather save just len+8 rather than than the subtraction.
>>>
>> Hmmmmmm, is this what you want?
>>        compression_counters.reduced_size += len - 8;
>>
>> Then calculate the real reduced size in populate_ram_info() where we return this
>> info to the user:
>>        info->compression->reduced_size = compression_counters.pages * PAGE_SIZE - compression_counters.reduced_size;
>>
>> Right?
> 
> I mean I'd rather see the actual size presented to the user rather than
> the saving compared to uncompressed.
> 

These statistics are used to help people to see whether compression works efficiently or not,
so maybe reduced-size is more straightforward? :)
diff mbox

Patch

diff --git a/hmp.c b/hmp.c
index ef93f4878b..5c2d3bd318 100644
--- a/hmp.c
+++ b/hmp.c
@@ -269,6 +269,19 @@  void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->xbzrle_cache->overflow);
     }
 
+    if (info->has_compression) {
+        monitor_printf(mon, "compression pages: %" PRIu64 " pages\n",
+                       info->compression->pages);
+        monitor_printf(mon, "compression busy: %" PRIu64 "\n",
+                       info->compression->busy);
+        monitor_printf(mon, "compression busy rate: %0.2f\n",
+                       info->compression->busy_rate);
+        monitor_printf(mon, "compression reduced size: %" PRIu64 "\n",
+                       info->compression->reduced_size);
+        monitor_printf(mon, "compression rate: %0.2f\n",
+                       info->compression->compression_rate);
+    }
+
     if (info->has_cpu_throttle_percentage) {
         monitor_printf(mon, "cpu throttle percentage: %" PRIu64 "\n",
                        info->cpu_throttle_percentage);
diff --git a/migration/migration.c b/migration/migration.c
index 05aec2c905..bf7c63a5a2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -693,6 +693,17 @@  static void populate_ram_info(MigrationInfo *info, MigrationState *s)
         info->xbzrle_cache->overflow = xbzrle_counters.overflow;
     }
 
+    if (migrate_use_compression()) {
+        info->has_compression = true;
+        info->compression = g_malloc0(sizeof(*info->compression));
+        info->compression->pages = compression_counters.pages;
+        info->compression->busy = compression_counters.busy;
+        info->compression->busy_rate = compression_counters.busy_rate;
+        info->compression->reduced_size = compression_counters.reduced_size;
+        info->compression->compression_rate =
+                                    compression_counters.compression_rate;
+    }
+
     if (cpu_throttle_active()) {
         info->has_cpu_throttle_percentage = true;
         info->cpu_throttle_percentage = cpu_throttle_get_percentage();
diff --git a/migration/ram.c b/migration/ram.c
index ee03b28435..80914b747e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -292,6 +292,15 @@  struct RAMState {
     uint64_t num_dirty_pages_period;
     /* xbzrle misses since the beginning of the period */
     uint64_t xbzrle_cache_miss_prev;
+
+    /* compression statistics since the beginning of the period */
+    /* amount of count that no free thread to compress data */
+    uint64_t compress_thread_busy_prev;
+    /* amount bytes reduced by compression */
+    uint64_t compress_reduced_size_prev;
+    /* amount of compressed pages */
+    uint64_t compress_pages_prev;
+
     /* number of iterations at the beginning of period */
     uint64_t iterations_prev;
     /* Iterations since start */
@@ -329,6 +338,8 @@  struct PageSearchStatus {
 };
 typedef struct PageSearchStatus PageSearchStatus;
 
+CompressionStats compression_counters;
+
 struct CompressParam {
     bool done;
     bool quit;
@@ -1147,6 +1158,24 @@  static void migration_update_rates(RAMState *rs, int64_t end_time)
             rs->xbzrle_cache_miss_prev) / iter_count;
         rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss;
     }
+
+    if (migrate_use_compression()) {
+        uint64_t comp_pages;
+
+        compression_counters.busy_rate = (double)(compression_counters.busy -
+            rs->compress_thread_busy_prev) / iter_count;
+        rs->compress_thread_busy_prev = compression_counters.busy;
+
+        comp_pages = compression_counters.pages - rs->compress_pages_prev;
+        if (comp_pages) {
+            compression_counters.compression_rate =
+                (double)(compression_counters.reduced_size -
+                rs->compress_reduced_size_prev) /
+                (comp_pages * TARGET_PAGE_SIZE);
+            rs->compress_pages_prev = compression_counters.pages;
+            rs->compress_reduced_size_prev = compression_counters.reduced_size;
+        }
+    }
 }
 
 static void migration_bitmap_sync(RAMState *rs)
@@ -1412,6 +1441,9 @@  static void flush_compressed_data(RAMState *rs)
         qemu_mutex_lock(&comp_param[idx].mutex);
         if (!comp_param[idx].quit) {
             len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
+            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
+            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;
+            compression_counters.pages++;
             ram_counters.transferred += len;
         }
         qemu_mutex_unlock(&comp_param[idx].mutex);
@@ -1441,6 +1473,10 @@  static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block,
             qemu_cond_signal(&comp_param[idx].cond);
             qemu_mutex_unlock(&comp_param[idx].mutex);
             pages = 1;
+            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
+            compression_counters.reduced_size += TARGET_PAGE_SIZE -
+                                                 bytes_xmit + 8;
+            compression_counters.pages++;
             ram_counters.transferred += bytes_xmit;
             break;
         }
@@ -1760,6 +1796,7 @@  static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
         if (res > 0) {
             return res;
         }
+        compression_counters.busy++;
     }
 
     return ram_save_page(rs, pss, last_stage);
diff --git a/migration/ram.h b/migration/ram.h
index d386f4d641..7b009b23e5 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -36,6 +36,7 @@ 
 
 extern MigrationStats ram_counters;
 extern XBZRLECacheStats xbzrle_counters;
+extern CompressionStats compression_counters;
 
 int xbzrle_cache_resize(int64_t new_size, Error **errp);
 uint64_t ram_bytes_remaining(void);
diff --git a/qapi/migration.json b/qapi/migration.json
index 3ec418dabf..a11987cdc4 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -72,6 +72,26 @@ 
            'cache-miss': 'int', 'cache-miss-rate': 'number',
            'overflow': 'int' } }
 
+##
+# @CompressionStats:
+#
+# Detailed compression migration statistics
+#
+# @pages: amount of pages compressed and transferred to the target VM
+#
+# @busy: amount of count that no free thread to compress data
+#
+# @busy-rate: rate of thread busy
+#
+# @reduced-size: amount of bytes reduced by compression
+#
+# @compression-rate: rate of compressed size
+#
+##
+{ 'struct': 'CompressionStats',
+  'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
+	   'reduced-size': 'int', 'compression-rate': 'number' } }
+
 ##
 # @MigrationStatus:
 #
@@ -169,6 +189,8 @@ 
 #           only present when the postcopy-blocktime migration capability
 #           is enabled. (Since 2.13)
 #
+# @compression: compression migration statistics, only returned if compression
+#           feature is on and status is 'active' or 'completed' (Since 2.14)
 #
 # Since: 0.14.0
 ##
@@ -183,7 +205,8 @@ 
            '*cpu-throttle-percentage': 'int',
            '*error-desc': 'str',
            '*postcopy-blocktime' : 'uint32',
-           '*postcopy-vcpu-blocktime': ['uint32']} }
+           '*postcopy-vcpu-blocktime': ['uint32'],
+           '*compression': 'CompressionStats'} }
 
 ##
 # @query-migrate: