[Qemu-devel] [PATCH v10 07/14, resend] rdma: introduce ram_handle_compressed()

[mrhines]

From: "Michael R. Hines" <address@hidden>

This gives RDMA shared access to madvise() on the destination side
when an entire chunk is found to be zero.

Reviewed-by: Paolo Bonzini <address@hidden>
Reviewed-by: Chegu Vinod <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Tested-by: Chegu Vinod <address@hidden>
Tested-by: Michael R. Hines <address@hidden>
Signed-off-by: Michael R. Hines <address@hidden>
---
 arch_init.c                   |   24 ++++++++++++++++--------
 include/migration/migration.h |    2 ++
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 819ca5a..2f1fdd3 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -782,6 +782,21 @@ static inline void *host_from_stream_offset(QEMUFile *f,
     return NULL;
 }
 
+/*
+ * If a page (or a whole RDMA chunk) has been
+ * determined to be zero, then zap it.
+ */
+void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
+{
+    memset(host, ch, TARGET_PAGE_SIZE);
+#ifndef _WIN32
+    if (ch == 0 && (!kvm_enabled() || kvm_has_sync_mmu()) &&
+                            getpagesize() <= TARGET_PAGE_SIZE) {
+        qemu_madvise(host, size, QEMU_MADV_DONTNEED);
+    }
+#endif
+}
+
 static int ram_load(QEMUFile *f, void *opaque, int version_id)
 {
     ram_addr_t addr;
@@ -849,14 +864,7 @@ static int ram_load(QEMUFile *f, void *opaque, int 
version_id)
             }
 
             ch = qemu_get_byte(f);
-            memset(host, ch, TARGET_PAGE_SIZE);
-#ifndef _WIN32
-            if (ch == 0 &&
-                (!kvm_enabled() || kvm_has_sync_mmu()) &&
-                getpagesize() <= TARGET_PAGE_SIZE) {
-                qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
-            }
-#endif
+            ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
         } else if (flags & RAM_SAVE_FLAG_PAGE) {
             void *host;
 
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 1eeaa40..110f4ad 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -108,6 +108,8 @@ uint64_t xbzrle_mig_pages_transferred(void);
 uint64_t xbzrle_mig_pages_overflow(void);
 uint64_t xbzrle_mig_pages_cache_miss(void);
 
+void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
+
 /**
  * @migrate_add_blocker - prevent migration from proceeding
  *
-- 
1.7.10.4