[Qemu-devel] [v4 02/13] migration: Add the framework of multi-thread compression

[Liang Li]

Add the code to create and destroy the multiple threads those will
be used to do data compression. Left some functions empty to keep
clearness, and the code will be added later.

Signed-off-by: Liang Li <address@hidden>
Signed-off-by: Yang Zhang <address@hidden>
---
 arch_init.c                   | 79 ++++++++++++++++++++++++++++++++++++++++++-
 include/migration/migration.h |  9 +++++
 migration/migration.c         | 37 ++++++++++++++++++++
 3 files changed, 124 insertions(+), 1 deletion(-)

diff --git a/arch_init.c b/arch_init.c
index 89c8fa4..1831f1a 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -332,6 +332,68 @@ static uint64_t migration_dirty_pages;
 static uint32_t last_version;
 static bool ram_bulk_stage;
 
+struct CompressParam {
+    /* To be done */
+};
+typedef struct CompressParam CompressParam;
+
+static CompressParam *comp_param;
+static bool quit_thread;
+
+static void *do_data_compress(void *opaque)
+{
+    while (!quit_thread) {
+
+    /* To be done */
+
+    }
+
+    return NULL;
+}
+
+static inline void terminate_compression_threads(void)
+{
+    quit_thread = true;
+
+    /* To be done */
+}
+
+void migrate_compress_threads_join(MigrationState *s)
+{
+    int i, thread_count;
+
+    if (!migrate_use_compression()) {
+        return;
+    }
+    terminate_compression_threads();
+    thread_count = migrate_compress_threads();
+    for (i = 0; i < thread_count; i++) {
+        qemu_thread_join(s->compress_thread + i);
+    }
+    g_free(s->compress_thread);
+    g_free(comp_param);
+    s->compress_thread = NULL;
+    comp_param = NULL;
+}
+
+void migrate_compress_threads_create(MigrationState *s)
+{
+    int i, thread_count;
+
+    if (!migrate_use_compression()) {
+        return;
+    }
+    quit_thread = false;
+    thread_count = migrate_compress_threads();
+    s->compress_thread = g_new0(QemuThread, thread_count);
+    comp_param = g_new0(CompressParam, thread_count);
+    for (i = 0; i < thread_count; i++) {
+        qemu_thread_create(s->compress_thread + i, "compress",
+                           do_data_compress, comp_param + i,
+                           QEMU_THREAD_JOINABLE);
+    }
+}
+
 /* Update the xbzrle cache to reflect a page that's been sent as all 0.
  * The important thing is that a stale (not-yet-0'd) page be replaced
  * by the new data.
@@ -645,6 +707,16 @@ static int ram_save_page(QEMUFile *f, RAMBlock* block, 
ram_addr_t offset,
     return bytes_sent;
 }
 
+static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
+                                    ram_addr_t offset, bool last_stage)
+{
+    int bytes_sent = 0;
+
+    /* To be done*/
+
+    return bytes_sent;
+}
+
 /*
  * ram_find_and_save_block: Finds a page to send and sends it to f
  *
@@ -679,7 +751,12 @@ static int ram_find_and_save_block(QEMUFile *f, bool 
last_stage)
                 ram_bulk_stage = false;
             }
         } else {
-            bytes_sent = ram_save_page(f, block, offset, last_stage);
+            if (migrate_use_compression()) {
+                bytes_sent = ram_save_compressed_page(f, block, offset,
+                                                      last_stage);
+            } else {
+                bytes_sent = ram_save_page(f, block, offset, last_stage);
+            }
 
             /* if page is unmodified, continue to the next */
             if (bytes_sent > 0) {
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 3cb5ba8..daf6c81 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -49,6 +49,9 @@ struct MigrationState
     QemuThread thread;
     QEMUBH *cleanup_bh;
     QEMUFile *file;
+    QemuThread *compress_thread;
+    int compress_thread_count;
+    int compress_level;
 
     int state;
     MigrationParams params;
@@ -107,6 +110,8 @@ bool migration_has_finished(MigrationState *);
 bool migration_has_failed(MigrationState *);
 MigrationState *migrate_get_current(void);
 
+void migrate_compress_threads_create(MigrationState *s);
+void migrate_compress_threads_join(MigrationState *s);
 uint64_t ram_bytes_remaining(void);
 uint64_t ram_bytes_transferred(void);
 uint64_t ram_bytes_total(void);
@@ -156,6 +161,10 @@ int64_t migrate_xbzrle_cache_size(void);
 
 int64_t xbzrle_cache_resize(int64_t new_size);
 
+bool migrate_use_compression(void);
+int migrate_compress_level(void);
+int migrate_compress_threads(void);
+
 void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
 void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
 void ram_control_load_hook(QEMUFile *f, uint64_t flags);
diff --git a/migration/migration.c b/migration/migration.c
index b3adbc6..309443e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -43,6 +43,11 @@ enum {
 #define BUFFER_DELAY     100
 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
 
+/* Default compression thread count */
+#define DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT 8
+/*0: means nocompress, 1: best speed, ... 9: best compress ratio */
+#define DEFAULT_MIGRATE_COMPRESS_LEVEL 1
+
 /* Migration XBZRLE default cache size */
 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
 
@@ -60,6 +65,8 @@ MigrationState *migrate_get_current(void)
         .bandwidth_limit = MAX_THROTTLE,
         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
         .mbps = -1,
+        .compress_thread_count = DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT,
+        .compress_level = DEFAULT_MIGRATE_COMPRESS_LEVEL,
     };
 
     return &current_migration;
@@ -302,6 +309,7 @@ static void migrate_fd_cleanup(void *opaque)
         qemu_thread_join(&s->thread);
         qemu_mutex_lock_iothread();
 
+        migrate_compress_threads_join(s);
         qemu_fclose(s->file);
         s->file = NULL;
     }
@@ -385,6 +393,8 @@ static MigrationState *migrate_init(const MigrationParams 
*params)
     int64_t bandwidth_limit = s->bandwidth_limit;
     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
+    int compress_level = s->compress_level;
+    int compress_thread_count = s->compress_thread_count;
 
     memcpy(enabled_capabilities, s->enabled_capabilities,
            sizeof(enabled_capabilities));
@@ -395,6 +405,8 @@ static MigrationState *migrate_init(const MigrationParams 
*params)
            sizeof(enabled_capabilities));
     s->xbzrle_cache_size = xbzrle_cache_size;
 
+    s->compress_level = compress_level;
+    s->compress_thread_count = compress_thread_count;
     s->bandwidth_limit = bandwidth_limit;
     s->state = MIG_STATE_SETUP;
     trace_migrate_set_state(MIG_STATE_SETUP);
@@ -567,6 +579,30 @@ bool migrate_zero_blocks(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 }
 
+bool migrate_use_compression(void)
+{
+    /* Disable compression before the patch series are applied */
+    return false;
+}
+
+int migrate_compress_level(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->compress_level;
+}
+
+int migrate_compress_threads(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->compress_thread_count;
+}
+
 int migrate_use_xbzrle(void)
 {
     MigrationState *s;
@@ -707,6 +743,7 @@ void migrate_fd_connect(MigrationState *s)
     /* Notify before starting migration thread */
     notifier_list_notify(&migration_state_notifiers, s);
 
+    migrate_compress_threads_create(s);
     qemu_thread_create(&s->thread, "migration", migration_thread, s,
                        QEMU_THREAD_JOINABLE);
 }
-- 
1.9.1