Generate new TBs without holding tb_lock, which should increase
scalability when running MTTCG for workloads that generate a lot
of code (e.g. booting linux).
XXX: Doesn't work :-) See the commit log from the previous patch.
Signed-off-by: Emilio G. Cota <c...@braap.org>
---
accel/tcg/cpu-exec.c | 8 +++++++-
accel/tcg/translate-all.c | 18 ++++++++++++++++--
2 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 54ecae2..47f0882 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -351,6 +351,7 @@ static inline TranslationBlock *tb_find(CPUState *cpu,
* single threaded the locks are NOPs.
*/
mmap_lock();
+#ifdef CONFIG_USER_ONLY
tb_lock();
have_tb_lock = true;
@@ -362,7 +363,12 @@ static inline TranslationBlock *tb_find(CPUState *cpu,
/* if no translated code available, then translate it now */
tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
}
-
+#else
+ /* tb_gen_code will acquire tb_lock.
+ * Just for the diff: note that have_tb_lock is local to tb_find!
*/
+ have_tb_lock = true;
+ tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
+#endif
mmap_unlock();
}
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 125b1a8..da29bcc 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -878,8 +878,6 @@ static TranslationBlock *tb_alloc(target_ulong pc)
{
TranslationBlock *tb;
- assert_tb_locked();
-
tb = tcg_tb_alloc(&tcg_ctx);
if (unlikely(tb == NULL)) {
return NULL;
@@ -1314,7 +1312,9 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
#ifdef CONFIG_PROFILER
int64_t ti;
#endif
+#ifdef CONFIG_USER_ONLY
assert_memory_lock();
+#endif
phys_pc = get_page_addr_code(env, pc);
if (use_icount && !(cflags & CF_IGNORE_ICOUNT)) {
@@ -1429,6 +1429,20 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
if ((pc & TARGET_PAGE_MASK) != virt_page2) {
phys_page2 = get_page_addr_code(env, virt_page2);
}
+ if (!have_tb_lock) {
+ TranslationBlock *t;
+
+ tb_lock();
+ /*
+ * There's a chance that our desired tb has been translated while
+ * we were translating it.
+ */
+ t = tb_htable_lookup(cpu, pc, cs_base, flags);
+ if (unlikely(t)) {
+ /* this is very unlikely so just waste the TB space we just used */
+ return t;
+ }
+ }
/* As long as consistency of the TB stuff is provided by tb_lock in user
* mode and is implicit in single-threaded softmmu emulation, no explicit
* memory barrier is required before tb_link_page() makes the TB visible
--
2.7.4
