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migration: move handle of zero page to the thread 

Detecting zero page is not a light work, moving it to the thread to
speed the main thread up, btw, handling ram_release_pages() for the
zero page is moved to the thread as well

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Xiao Guangrong 2018-08-21 16:10:24 +08:00 committed by Juan Quintela
parent 6ef3771c0d
commit 5e5fdcff28
1 changed files with 70 additions and 26 deletions
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96
migration/ram.c
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@ -341,6 +341,7 @@ typedef struct PageSearchStatus PageSearchStatus;
struct CompressParam {
bool done;
bool quit;
bool zero_page;
QEMUFile *file;
QemuMutex mutex;
QemuCond cond;
@ -382,7 +383,7 @@ static QemuThread *decompress_threads;
static QemuMutex decomp_done_lock;
static QemuCond decomp_done_cond;
static void do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
ram_addr_t offset, uint8_t *source_buf);
static void *do_data_compress(void *opaque)
@ -390,6 +391,7 @@ static void *do_data_compress(void *opaque)
CompressParam *param = opaque;
RAMBlock *block;
ram_addr_t offset;
bool zero_page;
qemu_mutex_lock(&param->mutex);
while (!param->quit) {
@ -399,11 +401,12 @@ static void *do_data_compress(void *opaque)
param->block = NULL;
qemu_mutex_unlock(&param->mutex);
do_compress_ram_page(param->file, &param->stream, block, offset,
param->originbuf);
zero_page = do_compress_ram_page(param->file, &param->stream,
block, offset, param->originbuf);
qemu_mutex_lock(&comp_done_lock);
param->done = true;
param->zero_page = zero_page;
qemu_cond_signal(&comp_done_cond);
qemu_mutex_unlock(&comp_done_lock);
@ -1849,13 +1852,19 @@ static int ram_save_multifd_page(RAMState *rs, RAMBlock *block,
return 1;
}
static void do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
ram_addr_t offset, uint8_t *source_buf)
{
RAMState *rs = ram_state;
uint8_t *p = block->host + (offset & TARGET_PAGE_MASK);
bool zero_page = false;
int ret;
if (save_zero_page_to_file(rs, f, block, offset)) {
zero_page = true;
goto exit;
}
save_page_header(rs, f, block, offset | RAM_SAVE_FLAG_COMPRESS_PAGE);
/*
@ -1868,10 +1877,21 @@ static void do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
if (ret < 0) {
qemu_file_set_error(migrate_get_current()->to_dst_file, ret);
error_report("compressed data failed!");
return;
return false;
}
exit:
ram_release_pages(block->idstr, offset & TARGET_PAGE_MASK, 1);
return zero_page;
}
static void
update_compress_thread_counts(const CompressParam *param, int bytes_xmit)
{
if (param->zero_page) {
ram_counters.duplicate++;
}
ram_counters.transferred += bytes_xmit;
}
static void flush_compressed_data(RAMState *rs)
@ -1895,7 +1915,12 @@ 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);
ram_counters.transferred += len;
/*
* it's safe to fetch zero_page without holding comp_done_lock
* as there is no further request submitted to the thread,
* i.e, the thread should be waiting for a request at this point.
*/
update_compress_thread_counts(&comp_param[idx], len);
}
qemu_mutex_unlock(&comp_param[idx].mutex);
}
@ -1926,7 +1951,7 @@ retry:
qemu_cond_signal(&comp_param[idx].cond);
qemu_mutex_unlock(&comp_param[idx].mutex);
pages = 1;
ram_counters.transferred += bytes_xmit;
update_compress_thread_counts(&comp_param[idx], bytes_xmit);
break;
}
}
@ -2200,6 +2225,39 @@ static bool save_page_use_compression(RAMState *rs)
return false;
}
/*
* try to compress the page before posting it out, return true if the page
* has been properly handled by compression, otherwise needs other
* paths to handle it
*/
static bool save_compress_page(RAMState *rs, RAMBlock *block, ram_addr_t offset)
{
if (!save_page_use_compression(rs)) {
return false;
}
/*
* When starting the process of a new block, the first page of
* the block should be sent out before other pages in the same
* block, and all the pages in last block should have been sent
* out, keeping this order is important, because the 'cont' flag
* is used to avoid resending the block name.
*
* We post the fist page as normal page as compression will take
* much CPU resource.
*/
if (block != rs->last_sent_block) {
flush_compressed_data(rs);
return false;
}
if (compress_page_with_multi_thread(rs, block, offset) > 0) {
return true;
}
return false;
}
/**
* ram_save_target_page: save one target page
*
@ -2220,15 +2278,8 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
return res;
}
/*
* When starting the process of a new block, the first page of
* the block should be sent out before other pages in the same
* block, and all the pages in last block should have been sent
* out, keeping this order is important, because the 'cont' flag
* is used to avoid resending the block name.
*/
if (block != rs->last_sent_block && save_page_use_compression(rs)) {
flush_compressed_data(rs);
if (save_compress_page(rs, block, offset)) {
return 1;
}
res = save_zero_page(rs, block, offset);
@ -2246,17 +2297,10 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
}
/*
* Make sure the first page is sent out before other pages.
*
* we post it as normal page as compression will take much
* CPU resource.
* do not use multifd for compression as the first page in the new
* block should be posted out before sending the compressed page
*/
if (block == rs->last_sent_block && save_page_use_compression(rs)) {
res = compress_page_with_multi_thread(rs, block, offset);
if (res > 0) {
return res;
}
} else if (migrate_use_multifd()) {
if (!save_page_use_compression(rs) && migrate_use_multifd()) {
return ram_save_multifd_page(rs, block, offset);
}