From: Hao Xiang <hao.xi...@linux.dev>
Multifd sender path gets an array of pages queued by the migration
thread. It performs zero page checking on every page in the array.
The pages are classfied as either a zero page or a normal page. This
change uses Intel DSA to offload the zero page checking from CPU to
the DSA accelerator. The sender thread submits a batch of pages to DSA
hardware and waits for the DSA completion thread to signal for work
completion.
Signed-off-by: Hao Xiang <hao.xi...@linux.dev>
Signed-off-by: Yichen Wang <yichen.w...@bytedance.com>
---
include/qemu/dsa.h | 4 +-
migration/migration.c | 2 +-
migration/multifd-zero-page.c | 100 ++++++++++++++++++++++++++++++++--
migration/multifd.c | 43 ++++++++++++++-
migration/multifd.h | 2 +-
util/dsa.c | 23 ++++----
6 files changed, 150 insertions(+), 24 deletions(-)
diff --git a/include/qemu/dsa.h b/include/qemu/dsa.h
index fd0305a7c7..a3b502ee41 100644
--- a/include/qemu/dsa.h
+++ b/include/qemu/dsa.h
@@ -83,7 +83,7 @@ typedef struct QemuDsaBatchTask {
*
* @return int Zero if successful, otherwise non zero.
*/
-int qemu_dsa_init(const char *dsa_parameter, Error **errp);
+int qemu_dsa_init(const strList *dsa_parameter, Error **errp);
/**
* @brief Start logic to enable using DSA.
@@ -146,7 +146,7 @@ static inline bool qemu_dsa_is_running(void)
return false;
}
-static inline int qemu_dsa_init(const char *dsa_parameter, Error **errp)
+static inline int qemu_dsa_init(const strList *dsa_parameter, Error **errp)
{
error_setg(errp, "DSA accelerator is not enabled.");
return -1;
diff --git a/migration/migration.c b/migration/migration.c
index 3dea06d577..085395b900 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3469,7 +3469,7 @@ static void *migration_thread(void *opaque)
object_ref(OBJECT(s));
update_iteration_initial_status(s);
- if (!multifd_send_setup()) {
+ if (!multifd_send_setup(&local_err)) {
goto out;
}
diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c
index e1b8370f88..ffb5611d44 100644
--- a/migration/multifd-zero-page.c
+++ b/migration/multifd-zero-page.c
@@ -37,25 +37,84 @@ static void swap_page_offset(ram_addr_t *pages_offset, int
a, int b)
}
/**
- * multifd_send_zero_page_detect: Perform zero page detection on all pages.
+ * zero_page_detect_cpu: Perform zero page detection using CPU.
*
* Sorts normal pages before zero pages in p->pages->offset and updates
* p->pages->normal_num.
*
* @param p A pointer to the send params.
*/
-void multifd_send_zero_page_detect(MultiFDSendParams *p)
+static void zero_page_detect_cpu(MultiFDSendParams *p)
{
MultiFDPages_t *pages = p->pages;
RAMBlock *rb = pages->block;
int i = 0;
int j = pages->num - 1;
- if (!multifd_zero_page_enabled()) {
- pages->normal_num = pages->num;
+ /*
+ * Sort the page offset array by moving all normal pages to
+ * the left and all zero pages to the right of the array.
+ */
+ while (i <= j) {
+ uint64_t offset = pages->offset[i];
+
+ if (!buffer_is_zero(rb->host + offset, p->page_size)) {
+ i++;
+ continue;
+ }
+
+ swap_page_offset(pages->offset, i, j);
+ ram_release_page(rb->idstr, offset);
+ j--;
+ }
+
+ pages->normal_num = i;
+}
+
+
+#ifdef CONFIG_DSA_OPT
+
+static void swap_result(bool *results, int a, int b)
+{
+ bool temp;
+
+ if (a == b) {
return;
}
+ temp = results[a];
+ results[a] = results[b];
+ results[b] = temp;
+}
+
+/**
+ * zero_page_detect_dsa: Perform zero page detection using
+ * Intel Data Streaming Accelerator (DSA).
+ *
+ * Sorts normal pages before zero pages in p->pages->offset and updates
+ * p->pages->normal_num.
+ *
+ * @param p A pointer to the send params.
+ */
+static void zero_page_detect_dsa(MultiFDSendParams *p)
+{
+ MultiFDPages_t *pages = p->pages;
+ RAMBlock *rb = pages->block;
+ bool *results = p->dsa_batch_task->results;
+
+ for (int i = 0; i < p->pages->num; i++) {
+ p->dsa_batch_task->addr[i] =
+ (ram_addr_t)(rb->host + p->pages->offset[i]);
+ }
+
+ buffer_is_zero_dsa_batch_sync(p->dsa_batch_task,
+ (const void **)p->dsa_batch_task->addr,
+ p->pages->num,
+ p->page_size);
+
+ int i = 0;
+ int j = pages->num - 1;
+
/*
* Sort the page offset array by moving all normal pages to
* the left and all zero pages to the right of the array.
@@ -63,11 +122,12 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p)
while (i <= j) {
uint64_t offset = pages->offset[i];
- if (!buffer_is_zero(rb->host + offset, p->page_size)) {
+ if (!results[i]) {
i++;
continue;
}
+ swap_result(results, i, j);
swap_page_offset(pages->offset, i, j);
ram_release_page(rb->idstr, offset);
j--;
@@ -76,6 +136,15 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p)
pages->normal_num = i;
}
+#else
+
+static void zero_page_detect_dsa(MultiFDSendParams *p)
+{
+ exit(1);
+}
+
+#endif
+
void multifd_recv_zero_page_process(MultiFDRecvParams *p)
{
for (int i = 0; i < p->zero_num; i++) {
@@ -87,3 +156,24 @@ void multifd_recv_zero_page_process(MultiFDRecvParams *p)
}
}
}
+
+/**
+ * multifd_send_zero_page_detect: Perform zero page detection on all pages.
+ *
+ * @param p A pointer to the send params.
+ */
+void multifd_send_zero_page_detect(MultiFDSendParams *p)
+{
+ MultiFDPages_t *pages = p->pages;
+
+ if (!multifd_zero_page_enabled()) {
+ pages->normal_num = pages->num;
+ return;
+ }
+
+ if (qemu_dsa_is_running()) {
+ zero_page_detect_dsa(p);
+ } else {
+ zero_page_detect_cpu(p);
+ }
+}
diff --git a/migration/multifd.c b/migration/multifd.c
index 6f8edd4b6a..014fee757a 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -817,6 +817,32 @@ static void multifd_send_cleanup_state(void)
multifd_send_state = NULL;
}
+static bool multifd_dsa_setup(MigrationState *s, const char *role, Error
**errp)
+{
+ /*
+ * Only setup DSA when needed. Currently, DSA is only used for zero page
+ * detection, which is only needed on sender side.
+ */
+ if (!s ||
+ s->parameters.zero_page_detection != ZERO_PAGE_DETECTION_DSA_ACCEL) {
+ return true;
+ }
+
+ const strList *dsa_parameter = migrate_dsa_accel_path();
+ if (qemu_dsa_init(dsa_parameter, errp)) {
+ error_setg(errp, "multifd: %s failed to initialize DSA.", role);
+ return false;
+ }
+ qemu_dsa_start();
+
+ return true;
+}
+
+static void multifd_dsa_cleanup(void)
+{
+ qemu_dsa_cleanup();
+}
+
void multifd_send_shutdown(void)
{
int i;
@@ -827,6 +853,8 @@ void multifd_send_shutdown(void)
multifd_send_terminate_threads();
+ multifd_dsa_cleanup();
+
for (i = 0; i < migrate_multifd_channels(); i++) {
MultiFDSendParams *p = &multifd_send_state->params[i];
Error *local_err = NULL;
@@ -1156,7 +1184,7 @@ static bool multifd_new_send_channel_create(gpointer
opaque, Error **errp)
return true;
}
-bool multifd_send_setup(void)
+bool multifd_send_setup(Error **errp)
{
MigrationState *s = migrate_get_current();
Error *local_err = NULL;
@@ -1169,6 +1197,10 @@ bool multifd_send_setup(void)
return true;
}
+ if (!multifd_dsa_setup(s, "Sender", errp)) {
+ return false;
+ }
+
thread_count = migrate_multifd_channels();
multifd_send_state = g_malloc0(sizeof(*multifd_send_state));
multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);
@@ -1395,6 +1427,7 @@ void multifd_recv_cleanup(void)
qemu_thread_join(&p->thread);
}
}
+ multifd_dsa_cleanup();
for (i = 0; i < migrate_multifd_channels(); i++) {
multifd_recv_cleanup_channel(&multifd_recv_state->params[i]);
}
@@ -1570,6 +1603,7 @@ int multifd_recv_setup(Error **errp)
uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
bool use_packets = multifd_use_packets();
uint8_t i;
+ int ret;
/*
* Return successfully if multiFD recv state is already initialised
@@ -1579,6 +1613,10 @@ int multifd_recv_setup(Error **errp)
return 0;
}
+ if (!multifd_dsa_setup(NULL, "Receiver", errp)) {
+ return -1;
+ }
+
thread_count = migrate_multifd_channels();
multifd_recv_state = g_malloc0(sizeof(*multifd_recv_state));
multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count);
@@ -1617,13 +1655,12 @@ int multifd_recv_setup(Error **errp)
for (i = 0; i < thread_count; i++) {
MultiFDRecvParams *p = &multifd_recv_state->params[i];
- int ret;
-
ret = multifd_recv_state->ops->recv_setup(p, errp);
if (ret) {
return ret;
}
}
+
return 0;
}
diff --git a/migration/multifd.h b/migration/multifd.h
index 027f57bf4e..871e3aa063 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -18,7 +18,7 @@
typedef struct MultiFDRecvData MultiFDRecvData;
-bool multifd_send_setup(void);
+bool multifd_send_setup(Error **errp);
void multifd_send_shutdown(void);
void multifd_send_channel_created(void);
int multifd_recv_setup(Error **errp);
diff --git a/util/dsa.c b/util/dsa.c
index 5aba1ae23a..44b1130a51 100644
--- a/util/dsa.c
+++ b/util/dsa.c
@@ -116,27 +116,27 @@ dsa_device_cleanup(QemuDsaDevice *instance)
*/
static int
dsa_device_group_init(QemuDsaDeviceGroup *group,
- const char *dsa_parameter,
+ const strList *dsa_parameter,
Error **errp)
{
- if (dsa_parameter == NULL || strlen(dsa_parameter) == 0) {
- return 0;
+ if (dsa_parameter == NULL) {
+ /* HACKING ALERT. */
+ /* return 0; */
+ dsa_parameter = &(strList) {
+ .value = (char *)"/dev/dsa/wq0.0", .next = NULL
+ };
}
int ret = 0;
- char *local_dsa_parameter = g_strdup(dsa_parameter);
const char *dsa_path[MAX_DSA_DEVICES];
int num_dsa_devices = 0;
- char delim[2] = " ";
- char *current_dsa_path = strtok(local_dsa_parameter, delim);
-
- while (current_dsa_path != NULL) {
- dsa_path[num_dsa_devices++] = current_dsa_path;
+ while (dsa_parameter) {
+ dsa_path[num_dsa_devices++] = dsa_parameter->value;
if (num_dsa_devices == MAX_DSA_DEVICES) {
break;
}
- current_dsa_path = strtok(NULL, delim);
+ dsa_parameter = dsa_parameter->next;
}
group->dsa_devices =
@@ -161,7 +161,6 @@ dsa_device_group_init(QemuDsaDeviceGroup *group,
}
exit:
- g_free(local_dsa_parameter);
return ret;
}
@@ -718,7 +717,7 @@ dsa_globals_init(void)
*
* @return int Zero if successful, otherwise non zero.
*/
-int qemu_dsa_init(const char *dsa_parameter, Error **errp)
+int qemu_dsa_init(const strList *dsa_parameter, Error **errp)
{
dsa_globals_init();
--
Yichen Wang
