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[Qemu-devel] [PATCH v10 8/9] Add set_cachesize command


From: Orit Wasserman
Subject: [Qemu-devel] [PATCH v10 8/9] Add set_cachesize command
Date: Wed, 16 May 2012 14:59:41 +0300

Change XBZRLE cache size in bytes (the size should be a power of 2).
If XBZRLE cache size is too small there will be many cache miss.

Signed-off-by: Benoit Hudzia <address@hidden>
Signed-off-by: Petter Svard <address@hidden>
Signed-off-by: Aidan Shribman <address@hidden>
Signed-off-by: Orit Wasserman <address@hidden>
---
 arch_init.c      |    7 +++++++
 hmp-commands.hx  |   15 +++++++++++++++
 hmp.c            |   13 +++++++++++++
 hmp.h            |    1 +
 migration.c      |   32 +++++++++++++++++++++++++++++++-
 migration.h      |    2 ++
 qapi-schema.json |   13 +++++++++++++
 qemu-common.h    |    5 +++++
 qmp-commands.hx  |   22 ++++++++++++++++++++++
 9 files changed, 109 insertions(+), 1 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 7ebdb7a..851e45d 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -24,6 +24,7 @@
 #include <stdint.h>
 #include <stdarg.h>
 #include <stdlib.h>
+#include <math.h>
 #ifndef _WIN32
 #include <sys/types.h>
 #include <sys/mman.h>
@@ -153,6 +154,12 @@ static struct {
     Cache *cache;
 } XBZRLE = {0};
 
+
+void xbzrle_cache_resize(int64_t order)
+{
+    cache_resize(XBZRLE.cache, pow(2, order));
+}
+
 static void save_block_hdr(QEMUFile *f, RAMBlock *block, ram_addr_t offset,
         int cont, int flag)
 {
diff --git a/hmp-commands.hx b/hmp-commands.hx
index e14e7be..abc9403 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -829,6 +829,21 @@ STEXI
 @item migrate_cancel
 @findex migrate_cancel
 Cancel the current VM migration.
+
+ETEXI
+
+    {
+        .name       = "migrate_set_cachesize",
+        .args_type  = "value:o",
+        .params     = "value",
+        .help       = "set cache size (in bytes) for XBZRLE migrations. The 
cache size effects the number of cache misses. In case of a high cache miss 
ratio you need to increase the cache size",
+        .mhandler.cmd = hmp_migrate_set_cachesize,
+    },
+
+STEXI
address@hidden migrate_set_cachesize @var{value}
address@hidden migrate_set_cache
+Set cache size to @var{value} (in bytes) for xbzrle migrations.
 ETEXI
 
     {
diff --git a/hmp.c b/hmp.c
index e73132b..0e4d63a 100644
--- a/hmp.c
+++ b/hmp.c
@@ -751,6 +751,19 @@ void hmp_migrate_set_downtime(Monitor *mon, const QDict 
*qdict)
     qmp_migrate_set_downtime(value, NULL);
 }
 
+void hmp_migrate_set_cachesize(Monitor *mon, const QDict *qdict)
+{
+    int64_t value = qdict_get_int(qdict, "value");
+    Error *err = NULL;
+
+    qmp_migrate_set_cachesize(value, &err);
+    if (err) {
+        monitor_printf(mon, "%s\n", error_get_pretty(err));
+        error_free(err);
+        return;
+    }
+}
+
 void hmp_migrate_set_speed(Monitor *mon, const QDict *qdict)
 {
     int64_t value = qdict_get_int(qdict, "value");
diff --git a/hmp.h b/hmp.h
index 5f9d842..9559559 100644
--- a/hmp.h
+++ b/hmp.h
@@ -53,6 +53,7 @@ void hmp_migrate_cancel(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_downtime(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_speed(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict);
+void hmp_migrate_set_cachesize(Monitor *mon, const QDict *qdict);
 void hmp_set_password(Monitor *mon, const QDict *qdict);
 void hmp_expire_password(Monitor *mon, const QDict *qdict);
 void hmp_eject(Monitor *mon, const QDict *qdict);
diff --git a/migration.c b/migration.c
index ba11adb..4fb3b8a 100644
--- a/migration.c
+++ b/migration.c
@@ -22,6 +22,7 @@
 #include "qemu_socket.h"
 #include "block-migration.h"
 #include "qmp-commands.h"
+#include <math.h>
 
 //#define DEBUG_MIGRATION
 
@@ -43,7 +44,7 @@ enum {
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
 
-/* Migration XBZRLE cache size */
+/* Migration XBZRLE default cache size */
 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
 
 static NotifierList migration_state_notifiers =
@@ -501,6 +502,35 @@ void qmp_migrate_cancel(Error **errp)
     migrate_fd_cancel(migrate_get_current());
 }
 
+void qmp_migrate_set_cachesize(int64_t value, Error **errp)
+{
+    MigrationState *s = migrate_get_current();
+
+    /* Check for truncation */
+    if (value != (size_t)value) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "exceeding address space");
+        return;
+    }
+
+    value = MIN(UINT64_MAX, value);
+
+    /* no change */
+    if (value == s->xbzrle_cache_size) {
+        return;
+    }
+
+    /* power of 2 */
+    if (value != 1 && !is_power_of_2(value)) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "needs to be power of 2");
+        return;
+    }
+
+    s->xbzrle_cache_size = value;
+    xbzrle_cache_resize(log2(value));
+}
+
 void qmp_migrate_set_speed(int64_t value, Error **errp)
 {
     MigrationState *s;
diff --git a/migration.h b/migration.h
index 175c729..6a5bc0e 100644
--- a/migration.h
+++ b/migration.h
@@ -106,4 +106,6 @@ int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t 
*dst, int dlen);
 int migrate_use_xbzrle(void);
 int64_t migrate_xbzrle_cache_size(void);
 
+void xbzrle_cache_resize(int64_t new_size);
+
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 2887c51..4d30552 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1357,6 +1357,19 @@
 { 'command': 'migrate_set_speed', 'data': {'value': 'int'} }
 
 ##
+# @migrate_set_cachesize
+#
+# Set XBZRLE cache size
+#
+# @value: cache size in bytes
+#
+# Returns: nothing on success
+#
+# Since: 1.1
+##
+{ 'command': 'migrate_set_cachesize', 'data': {'value': 'int'} }
+
+##
 # @ObjectPropertyInfo:
 #
 # @name: the name of the property
diff --git a/qemu-common.h b/qemu-common.h
index 3d0f66f..da44c17 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -415,4 +415,9 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b, 
uint32_t c)
 int uleb128_encode_small(uint8_t *out, uint32_t n);
 int uleb128_decode_small(const uint8_t *in, uint32_t *n);
 
+static inline bool is_power_of_2(int64_t value)
+{
+    return !(value & (value - 1));
+}
+
 #endif
diff --git a/qmp-commands.hx b/qmp-commands.hx
index f276e08..3bdbaae 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -520,6 +520,28 @@ Example:
 <- { "return": {} }
 
 EQMP
+{
+        .name       = "migrate_set_cachesize",
+        .args_type  = "value:o",
+        .mhandler.cmd_new = qmp_marshal_input_migrate_set_cachesize,
+    },
+
+SQMP
+migrate_set_cachesize
+---------------------
+
+Set cache size to be used by XBZRLE migration
+
+Arguments:
+
+- "value": cache size in bytes (json-int)
+
+Example:
+
+-> { "execute": "migrate_set_cachesize", "arguments": { "value": 512 } }
+<- { "return": {} }
+
+EQMP
 
     {
         .name       = "migrate_set_speed",
-- 
1.7.7.6




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