[Qemu-devel] [v6 03/14] migration: Add the framework of multi-thread decompression

[Liang Li <liang.z.li@intel.com>]

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

Signed-off-by: Liang Li <liang.z.li@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Reviewed-by: Dr.David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
---
 arch_init.c                   | 77 +++++++++++++++++++++++++++++++++++++++++++
 include/migration/migration.h |  4 +++
 migration/migration.c         | 19 +++++++++++
 3 files changed, 100 insertions(+)

diff --git a/arch_init.c b/arch_init.c
index 179c58c..8749481 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -24,6 +24,7 @@
 #include <stdint.h>
 #include <stdarg.h>
 #include <stdlib.h>
+#include <zlib.h>
 #ifndef _WIN32
 #include <sys/types.h>
 #include <sys/mman.h>
@@ -127,6 +128,7 @@ static uint64_t bitmap_sync_count;
 #define RAM_SAVE_FLAG_CONTINUE 0x20
 #define RAM_SAVE_FLAG_XBZRLE   0x40
 /* 0x80 is reserved in migration.h start with 0x100 next */
+#define RAM_SAVE_FLAG_COMPRESS_PAGE    0x100
 
 static struct defconfig_file {
     const char *filename;
@@ -321,9 +323,18 @@ struct CompressParam {
 };
 typedef struct CompressParam CompressParam;
 
+struct DecompressParam {
+    /* To be done */
+};
+typedef struct DecompressParam DecompressParam;
+
 static CompressParam *comp_param;
 static QemuThread *compress_threads;
 static bool quit_comp_thread;
+static bool quit_decomp_thread;
+static DecompressParam *decomp_param;
+static QemuThread *decompress_threads;
+static uint8_t *compressed_data_buf;
 
 static void *do_data_compress(void *opaque)
 {
@@ -1203,10 +1214,59 @@ void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
     }
 }
 
+static void *do_data_decompress(void *opaque)
+{
+    while (!quit_decomp_thread) {
+        /* To be done */
+    }
+
+    return NULL;
+}
+
+void migrate_decompress_threads_create(void)
+{
+    int i, thread_count;
+
+    thread_count = migrate_decompress_threads();
+    decompress_threads = g_new0(QemuThread, thread_count);
+    decomp_param = g_new0(DecompressParam, thread_count);
+    compressed_data_buf = g_malloc0(compressBound(TARGET_PAGE_SIZE));
+    quit_decomp_thread = false;
+    for (i = 0; i < thread_count; i++) {
+        qemu_thread_create(decompress_threads + i, "decompress",
+                           do_data_decompress, decomp_param + i,
+                           QEMU_THREAD_JOINABLE);
+    }
+}
+
+void migrate_decompress_threads_join(void)
+{
+    int i, thread_count;
+
+    quit_decomp_thread = true;
+    thread_count = migrate_decompress_threads();
+    for (i = 0; i < thread_count; i++) {
+        qemu_thread_join(decompress_threads + i);
+    }
+    g_free(decompress_threads);
+    g_free(decomp_param);
+    g_free(compressed_data_buf);
+    decompress_threads = NULL;
+    decomp_param = NULL;
+    compressed_data_buf = NULL;
+}
+
+static void decompress_data_with_multi_threads(uint8_t *compbuf,
+                                               void *host, int len)
+{
+    /* To be done */
+}
+
 static int ram_load(QEMUFile *f, void *opaque, int version_id)
 {
     int flags = 0, ret = 0;
     static uint64_t seq_iter;
+    int len = 0;
 
     seq_iter++;
 
@@ -1286,6 +1346,23 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
             }
             qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
             break;
+        case RAM_SAVE_FLAG_COMPRESS_PAGE:
+            host = host_from_stream_offset(f, addr, flags);
+            if (!host) {
+                error_report("Invalid RAM offset " RAM_ADDR_FMT, addr);
+                ret = -EINVAL;
+                break;
+            }
+
+            len = qemu_get_be32(f);
+            if (len < 0 || len > compressBound(TARGET_PAGE_SIZE)) {
+                error_report("Invalid compressed data length: %d", len);
+                ret = -EINVAL;
+                break;
+            }
+            qemu_get_buffer(f, compressed_data_buf, len);
+            decompress_data_with_multi_threads(compressed_data_buf, host, len);
+            break;
         case RAM_SAVE_FLAG_XBZRLE:
             host = host_from_stream_offset(f, addr, flags);
             if (!host) {
diff --git a/include/migration/migration.h b/include/migration/migration.h
index a3ebbf6..d4a1062 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -51,6 +51,7 @@ struct MigrationState
     QEMUBH *cleanup_bh;
     QEMUFile *file;
     int compress_thread_count;
+    int decompress_thread_count;
     int compress_level;
 
     int state;
@@ -108,6 +109,8 @@ MigrationState *migrate_get_current(void);
 
 void migrate_compress_threads_create(void);
 void migrate_compress_threads_join(void);
+void migrate_decompress_threads_create(void);
+void migrate_decompress_threads_join(void);
 uint64_t ram_bytes_remaining(void);
 uint64_t ram_bytes_transferred(void);
 uint64_t ram_bytes_total(void);
@@ -159,6 +162,7 @@ int64_t xbzrle_cache_resize(int64_t new_size);
 bool migrate_use_compression(void);
 int migrate_compress_level(void);
 int migrate_compress_threads(void);
+int migrate_decompress_threads(void);
 
 void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
 void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
diff --git a/migration/migration.c b/migration/migration.c
index 5a8b5a7..19409e6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -35,6 +35,9 @@
 
 /* Default compression thread count */
 #define DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT 8
+/* Default decompression thread count, usually decompression is at
+ * least 4 times as fast as compression.*/
+#define DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT 2
 /*0: means nocompress, 1: best speed, ... 9: best compress ratio */
 #define DEFAULT_MIGRATE_COMPRESS_LEVEL 1
 
@@ -58,6 +61,7 @@ MigrationState *migrate_get_current(void)
         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
         .mbps = -1,
         .compress_thread_count = DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT,
+        .decompress_thread_count = DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT,
         .compress_level = DEFAULT_MIGRATE_COMPRESS_LEVEL,
     };
 
@@ -113,6 +117,7 @@ static void process_incoming_migration_co(void *opaque)
     free_xbzrle_decoded_buf();
     if (ret < 0) {
         error_report("load of migration failed: %s", strerror(-ret));
+        migrate_decompress_threads_join();
         exit(EXIT_FAILURE);
     }
     qemu_announce_self();
@@ -121,6 +126,7 @@ static void process_incoming_migration_co(void *opaque)
     bdrv_invalidate_cache_all(&local_err);
     if (local_err) {
         error_report_err(local_err);
+        migrate_decompress_threads_join();
         exit(EXIT_FAILURE);
     }
 
@@ -129,6 +135,7 @@ static void process_incoming_migration_co(void *opaque)
     } else {
         runstate_set(RUN_STATE_PAUSED);
     }
+    migrate_decompress_threads_join();
 }
 
 void process_incoming_migration(QEMUFile *f)
@@ -137,6 +144,7 @@ void process_incoming_migration(QEMUFile *f)
     int fd = qemu_get_fd(f);
 
     assert(fd != -1);
+    migrate_decompress_threads_create();
     qemu_set_nonblock(fd);
     qemu_coroutine_enter(co, f);
 }
@@ -400,6 +408,7 @@ static MigrationState *migrate_init(const MigrationParams *params)
     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
     int compress_level = s->compress_level;
     int compress_thread_count = s->compress_thread_count;
+    int decompress_thread_count = s->decompress_thread_count;
 
     memcpy(enabled_capabilities, s->enabled_capabilities,
            sizeof(enabled_capabilities));
@@ -412,6 +421,7 @@ static MigrationState *migrate_init(const MigrationParams *params)
 
     s->compress_level = compress_level;
     s->compress_thread_count = compress_thread_count;
+    s->decompress_thread_count = decompress_thread_count;
     s->bandwidth_limit = bandwidth_limit;
     s->state = MIGRATION_STATUS_SETUP;
     trace_migrate_set_state(MIGRATION_STATUS_SETUP);
@@ -623,6 +633,15 @@ int migrate_compress_threads(void)
     return s->compress_thread_count;
 }
 
+int migrate_decompress_threads(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->decompress_thread_count;
+}
+
 int migrate_use_xbzrle(void)
 {
     MigrationState *s;
-- 
1.9.1