While 32mb is certainly usable a full system boot ends up flushing the
codegen buffer nearly 100 times. Increase the default on 64 bit hosts
to take advantage of all that spare memory. After this change I can
boot my tests system without any TB flushes.
As we usually run more CONFIG_USER binaries at a time in typical usage
we aren't quite as profligate for user-mode code generation usage. We
also bring the static code gen defies to the same place to keep all
the reasoning in the comments together.
Signed-off-by: Alex Bennée <address@hidden>
Tested-by: Niek Linnenbank <address@hidden>
- 2gb->1gb for system emulation
- split user and system emulation buffer sizes
accel/tcg/translate-all.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 4ce5d1b3931..78914154bfc 100644
@@ -892,15 +892,6 @@ static void page_lock_pair(PageDesc **ret_p1, tb_page_addr_t phys1,
-#if defined(CONFIG_USER_ONLY) && TCG_TARGET_REG_BITS == 32
- * For user mode on smaller 32 bit systems we may run into trouble
- * allocating big chunks of data in the right place. On these systems
- * we utilise a static code generation buffer directly in the binary.
/* Minimum size of the code gen buffer. This number is randomly chosen,
but not so small that we can't have a fair number of TB's live. */
#define MIN_CODE_GEN_BUFFER_SIZE (1 * MiB)
@@ -929,7 +920,33 @@ static void page_lock_pair(PageDesc **ret_p1, tb_page_addr_t phys1,
# define MAX_CODE_GEN_BUFFER_SIZE ((size_t)-1)
+#if TCG_TARGET_REG_BITS == 32
#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (32 * MiB)
+ * For user mode on smaller 32 bit systems we may run into trouble
+ * allocating big chunks of data in the right place. On these systems
+ * we utilise a static code generation buffer directly in the binary.
+#else /* TCG_TARGET_REG_BITS == 64 */
+ * As user-mode emulation typically means running multiple instances
+ * of the translator don't go too nuts with our default code gen
+ * buffer lest we make things too hard for the OS.
+#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (128 * MiB)
+ * We expect most system emulation to run one or two guests per host.
+ * Users running large scale system emulation may want to tweak their
+ * runtime setup via the tb-size control on the command line.
+#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (1 * GiB)
#define DEFAULT_CODE_GEN_BUFFER_SIZE \
(DEFAULT_CODE_GEN_BUFFER_SIZE_1 < MAX_CODE_GEN_BUFFER_SIZE \