@@ -318,8 +318,13 @@ void migrate_compress_threads_join(void)
if (!migrate_use_compression()) {
return;
}
- terminate_compression_threads();
+
thread_count = migrate_compress_threads();
+ if (thread_count == 1) {
+ return;
+ }
+
+ terminate_compression_threads();
for (i = 0; i < thread_count; i++) {
qemu_thread_join(compress_threads + i);
qemu_fclose(comp_param[i].file);
@@ -345,9 +350,12 @@ void migrate_compress_threads_create(void)
if (!migrate_use_compression()) {
return;
}
+ thread_count = migrate_compress_threads();
+ if (thread_count == 1) {
+ return;
+ }
quit_comp_thread = false;
compression_switch = true;
- thread_count = migrate_compress_threads();
compress_threads = g_new0(QemuThread, thread_count);
comp_param = g_new0(CompressParam, thread_count);
comp_done_cond = g_new0(QemuCond, 1);
@@ -782,6 +790,9 @@ static void flush_compressed_data(QEMUFile *f)
return;
}
thread_count = migrate_compress_threads();
+ if (thread_count == 1) {
+ return;
+ }
for (idx = 0; idx < thread_count; idx++) {
if (!comp_param[idx].done) {
qemu_mutex_lock(comp_done_lock);
@@ -883,18 +894,16 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
* out, keeping this order is important, because the 'cont' flag
* is used to avoid resending the block name.
*/
- if (block != last_sent_block) {
+ if (block != last_sent_block || migrate_compress_threads() == 1) {
flush_compressed_data(f);
pages = save_zero_page(f, block, offset, p, bytes_transferred);
if (pages == -1) {
- set_compress_params(&comp_param[0], block, offset);
- /* Use the qemu thread to compress the data to make sure the
- * first page is sent out before other pages
- */
- bytes_xmit = do_compress_ram_page(&comp_param[0]);
- acct_info.norm_pages++;
- qemu_put_qemu_file(f, comp_param[0].file);
+ bytes_xmit = save_page_header(f, block, offset |
+ RAM_SAVE_FLAG_COMPRESS_PAGE);
+ bytes_xmit += qemu_put_compression_data(f, p, TARGET_PAGE_SIZE,
+ migrate_compress_level());
*bytes_transferred += bytes_xmit;
+ acct_info.norm_pages++;
pages = 1;
}
} else {
When the compression thread count is set to 1, the current implementation is inefficient because of the following reason: 1. Thread synchronization cost; 2. Data copy; 3. No benefit from the separate compression thread; This patch optimizes the performance for the case of 1 compress thread. In this case, the compression is done in the migration thread, for some fast compression algorithm, it can help to improve the performance. Signed-off-by: Liang Li <liang.z.li@intel.com> --- migration/ram.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)