When loading a zero page, check whether it will be loaded to
persistent memory If yes, load it by libpmem function
pmem_memset_nodrain(). Combined with a call to pmem_drain() at the
end of RAM loading, we can guarantee all those zero pages are
persistently loaded.
Depending on the host HW/SW configurations, pmem_drain() can be
"sfence". Therefore, we do not call pmem_drain() after each
pmem_memset_nodrain(), or use pmem_memset_persist() (equally
pmem_memset_nodrain() + pmem_drain()), in order to avoid unnecessary
overhead.
Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com>
---
include/qemu/pmem.h | 2 ++
migration/ram.c | 25 +++++++++++++++++++++----
migration/ram.h | 2 +-
migration/rdma.c | 2 +-
stubs/pmem.c | 9 +++++++++
5 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/include/qemu/pmem.h b/include/qemu/pmem.h
index 16f5b2653a..ce96379f3c 100644
--- a/include/qemu/pmem.h
+++ b/include/qemu/pmem.h
@@ -17,6 +17,8 @@
#else /* !CONFIG_LIBPMEM */
void *pmem_memcpy_persist(void *pmemdest, const void *src, size_t len);
+void *pmem_memset_nodrain(void *pmemdest, int c, size_t len);
+void pmem_drain(void);
#endif /* CONFIG_LIBPMEM */
diff --git a/migration/ram.c b/migration/ram.c
index 5e33e5cc79..3904ceee79 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -51,6 +51,7 @@
#include "qemu/rcu_queue.h"
#include "migration/colo.h"
#include "migration/block.h"
+#include "qemu/pmem.h"
/***********************************************************/
/* ram save/restore */
@@ -2479,11 +2480,16 @@ static inline void *host_from_ram_block_offset(RAMBlock
*block,
* @host: host address for the zero page
* @ch: what the page is filled from. We only support zero
* @size: size of the zero page
+ * @is_pmem: whether @host is in the persistent memory
*/
-void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
+void ram_handle_compressed(void *host, uint8_t ch, uint64_t size, bool is_pmem)
{
if (ch != 0 || !is_zero_range(host, size)) {
- memset(host, ch, size);
+ if (!is_pmem) {
+ memset(host, ch, size);
+ } else {
+ pmem_memset_nodrain(host, ch, size);
+ }
}
}
@@ -2839,6 +2845,7 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
bool postcopy_running = postcopy_is_running();
/* ADVISE is earlier, it shows the source has the postcopy capability on */
bool postcopy_advised = postcopy_is_advised();
+ bool need_pmem_drain = false;
seq_iter++;
@@ -2864,6 +2871,8 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
ram_addr_t addr, total_ram_bytes;
void *host = NULL;
uint8_t ch;
+ RAMBlock *block = NULL;
+ bool is_pmem = false;
addr = qemu_get_be64(f);
flags = addr & ~TARGET_PAGE_MASK;
@@ -2880,7 +2889,7 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
- RAMBlock *block = ram_block_from_stream(f, flags);
+ block = ram_block_from_stream(f, flags);
host = host_from_ram_block_offset(block, addr);
if (!host) {
@@ -2890,6 +2899,9 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
}
ramblock_recv_bitmap_set(block, host);
trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host);
+
+ is_pmem = ramblock_is_pmem(block);
+ need_pmem_drain = need_pmem_drain || is_pmem;
}
switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
@@ -2943,7 +2955,7 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
- ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
+ ram_handle_compressed(host, ch, TARGET_PAGE_SIZE, is_pmem);
break;
case RAM_SAVE_FLAG_PAGE:
@@ -2986,6 +2998,11 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
}
wait_for_decompress_done();
+
+ if (need_pmem_drain) {
+ pmem_drain();
+ }
+
rcu_read_unlock();
trace_ram_load_complete(ret, seq_iter);
return ret;
diff --git a/migration/ram.h b/migration/ram.h
index f3a227b4fc..18934ae9e4 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -57,7 +57,7 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms);
int ram_discard_range(const char *block_name, uint64_t start, size_t length);
int ram_postcopy_incoming_init(MigrationIncomingState *mis);
-void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
+void ram_handle_compressed(void *host, uint8_t ch, uint64_t size, bool
is_pmem);
int ramblock_recv_bitmap_test(RAMBlock *rb, void *host_addr);
void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr);
diff --git a/migration/rdma.c b/migration/rdma.c
index da474fc19f..573bcd2cb0 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3229,7 +3229,7 @@ static int qemu_rdma_registration_handle(QEMUFile *f,
void *opaque)
host_addr = block->local_host_addr +
(comp->offset - block->offset);
- ram_handle_compressed(host_addr, comp->value, comp->length);
+ ram_handle_compressed(host_addr, comp->value, comp->length, false);
break;
case RDMA_CONTROL_REGISTER_FINISHED:
diff --git a/stubs/pmem.c b/stubs/pmem.c
index 03d990e571..a65b3bfc6b 100644
--- a/stubs/pmem.c
+++ b/stubs/pmem.c
@@ -17,3 +17,12 @@ void *pmem_memcpy_persist(void *pmemdest, const void *src,
size_t len)
{
return memcpy(pmemdest, src, len);
}
+
+void *pmem_memset_nodrain(void *pmemdest, int c, size_t len)
+{
+ return memset(pmemdest, c, len);
+}
+
+void pmem_drain(void)
+{
+}
--
2.14.1
