* Wei Wang (wei.w.w...@intel.com) wrote: > Users may need to check the xbzrle encoding rate to know if the guest > memory is xbzrle encoding-friendly, and dynamically turn off the > encoding if the encoding rate is low. > > Signed-off-by: Yi Sun <yi.y....@intel.com> > Signed-off-by: Wei Wang <wei.w.w...@intel.com>
Queued > --- > migration/migration.c | 1 + > migration/ram.c | 39 +++++++++++++++++++++++++++++++++++++-- > monitor/hmp-cmds.c | 2 ++ > qapi/migration.json | 5 ++++- > 4 files changed, 44 insertions(+), 3 deletions(-) > > diff --git a/migration/migration.c b/migration/migration.c > index 187ac0410c..e40421353c 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -930,6 +930,7 @@ static void populate_ram_info(MigrationInfo *info, > MigrationState *s) > info->xbzrle_cache->pages = xbzrle_counters.pages; > info->xbzrle_cache->cache_miss = xbzrle_counters.cache_miss; > info->xbzrle_cache->cache_miss_rate = > xbzrle_counters.cache_miss_rate; > + info->xbzrle_cache->encoding_rate = xbzrle_counters.encoding_rate; > info->xbzrle_cache->overflow = xbzrle_counters.overflow; > } > > diff --git a/migration/ram.c b/migration/ram.c > index 04f13feb2e..41b75a0a0f 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -327,6 +327,10 @@ struct RAMState { > uint64_t num_dirty_pages_period; > /* xbzrle misses since the beginning of the period */ > uint64_t xbzrle_cache_miss_prev; > + /* Amount of xbzrle pages since the beginning of the period */ > + uint64_t xbzrle_pages_prev; > + /* Amount of xbzrle encoded bytes since the beginning of the period */ > + uint64_t xbzrle_bytes_prev; > > /* compression statistics since the beginning of the period */ > /* amount of count that no free thread to compress data */ > @@ -696,6 +700,18 @@ static int save_xbzrle_page(RAMState *rs, uint8_t > **current_data, > return -1; > } > > + /* > + * Reaching here means the page has hit the xbzrle cache, no matter what > + * encoding result it is (normal encoding, overflow or skipping the > page), > + * count the page as encoded. This is used to caculate the encoding rate. > + * > + * Example: 2 pages (8KB) being encoded, first page encoding generates > 2KB, > + * 2nd page turns out to be skipped (i.e. no new bytes written to the > + * page), the overall encoding rate will be 8KB / 2KB = 4, which has the > + * skipped page included. In this way, the encoding rate can tell if the > + * guest page is good for xbzrle encoding. > + */ > + xbzrle_counters.pages++; > prev_cached_page = get_cached_data(XBZRLE.cache, current_addr); > > /* save current buffer into memory */ > @@ -726,6 +742,7 @@ static int save_xbzrle_page(RAMState *rs, uint8_t > **current_data, > } else if (encoded_len == -1) { > trace_save_xbzrle_page_overflow(); > xbzrle_counters.overflow++; > + xbzrle_counters.bytes += TARGET_PAGE_SIZE; > return -1; > } > > @@ -736,8 +753,12 @@ static int save_xbzrle_page(RAMState *rs, uint8_t > **current_data, > qemu_put_be16(rs->f, encoded_len); > qemu_put_buffer(rs->f, XBZRLE.encoded_buf, encoded_len); > bytes_xbzrle += encoded_len + 1 + 2; > - xbzrle_counters.pages++; > - xbzrle_counters.bytes += bytes_xbzrle; > + /* > + * Like compressed_size (please see update_compress_thread_counts), > + * the xbzrle encoded bytes don't count the 8 byte header with > + * RAM_SAVE_FLAG_CONTINUE. > + */ > + xbzrle_counters.bytes += bytes_xbzrle - 8; > ram_counters.transferred += bytes_xbzrle; > > return 1; > @@ -870,9 +891,23 @@ static void migration_update_rates(RAMState *rs, int64_t > end_time) > } > > if (migrate_use_xbzrle()) { > + double encoded_size, unencoded_size; > + > xbzrle_counters.cache_miss_rate = > (double)(xbzrle_counters.cache_miss - > rs->xbzrle_cache_miss_prev) / page_count; > rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss; > + unencoded_size = (xbzrle_counters.pages - rs->xbzrle_pages_prev) * > + TARGET_PAGE_SIZE; > + encoded_size = xbzrle_counters.bytes - rs->xbzrle_bytes_prev; > + if (xbzrle_counters.pages == rs->xbzrle_pages_prev) { > + xbzrle_counters.encoding_rate = 0; > + } else if (!encoded_size) { > + xbzrle_counters.encoding_rate = UINT64_MAX; > + } else { > + xbzrle_counters.encoding_rate = unencoded_size / encoded_size; > + } > + rs->xbzrle_pages_prev = xbzrle_counters.pages; > + rs->xbzrle_bytes_prev = xbzrle_counters.bytes; > } > > if (migrate_use_compression()) { > diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c > index 9b94e67879..c2a3a667ae 100644 > --- a/monitor/hmp-cmds.c > +++ b/monitor/hmp-cmds.c > @@ -303,6 +303,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) > info->xbzrle_cache->cache_miss); > monitor_printf(mon, "xbzrle cache miss rate: %0.2f\n", > info->xbzrle_cache->cache_miss_rate); > + monitor_printf(mon, "xbzrle encoding rate: %0.2f\n", > + info->xbzrle_cache->encoding_rate); > monitor_printf(mon, "xbzrle overflow: %" PRIu64 "\n", > info->xbzrle_cache->overflow); > } > diff --git a/qapi/migration.json b/qapi/migration.json > index eca2981d0a..358e40226d 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -70,6 +70,8 @@ > # > # @cache-miss-rate: rate of cache miss (since 2.1) > # > +# @encoding-rate: rate of encoded bytes (since 5.1) > +# > # @overflow: number of overflows > # > # Since: 1.2 > @@ -77,7 +79,7 @@ > { 'struct': 'XBZRLECacheStats', > 'data': {'cache-size': 'int', 'bytes': 'int', 'pages': 'int', > 'cache-miss': 'int', 'cache-miss-rate': 'number', > - 'overflow': 'int' } } > + 'encoding-rate': 'number', 'overflow': 'int' } } > > ## > # @CompressionStats: > @@ -337,6 +339,7 @@ > # "pages":2444343, > # "cache-miss":2244, > # "cache-miss-rate":0.123, > +# "encoding-rate":80.1, > # "overflow":34434 > # } > # } > -- > 2.20.1 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK