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[Qemu-devel] [PATCH 08/10] tcg: Avoid bouncing tb_lock between tb_gen_co
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 08/10] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump() |
Date: |
Tue, 19 Jul 2016 10:32:19 +0200 |
From: Sergey Fedorov <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
cpu-exec.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index 7ca2b71..bd9fa5a 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -282,7 +282,8 @@ static TranslationBlock *tb_find_physical(CPUState *cpu,
static TranslationBlock *tb_find_slow(CPUState *cpu,
target_ulong pc,
target_ulong cs_base,
- uint32_t flags)
+ uint32_t flags,
+ bool *have_tb_lock)
{
TranslationBlock *tb;
@@ -295,6 +296,7 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
*/
mmap_lock();
tb_lock();
+ *have_tb_lock = true;
/* There's a chance that our desired tb has been translated while
* taking the locks so we check again inside the lock.
@@ -305,7 +307,6 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
}
- tb_unlock();
mmap_unlock();
}
@@ -322,6 +323,7 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu,
TranslationBlock *tb;
target_ulong cs_base, pc;
uint32_t flags;
+ bool have_tb_lock = false;
/* we record a subset of the CPU state. It will
always be the same before a given translated block
@@ -330,7 +332,7 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu,
tb = atomic_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]);
if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
tb->flags != flags)) {
- tb = tb_find_slow(cpu, pc, cs_base, flags);
+ tb = tb_find_slow(cpu, pc, cs_base, flags, &have_tb_lock);
}
#ifndef CONFIG_USER_ONLY
/* We don't take care of direct jumps when address mapping changes in
@@ -343,13 +345,18 @@ static inline TranslationBlock *tb_find_fast(CPUState
*cpu,
#endif
/* See if we can patch the calling TB. */
if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
- tb_lock();
+ if (!have_tb_lock) {
+ tb_lock();
+ have_tb_lock = true;
+ }
/* Check if translation buffer has been flushed */
if (cpu->tb_flushed) {
cpu->tb_flushed = false;
} else if (!tb->invalid) {
tb_add_jump(last_tb, tb_exit, tb);
}
+ }
+ if (have_tb_lock) {
tb_unlock();
}
return tb;
--
2.7.4
- [Qemu-devel] [PATCH v5 00/10] Reduce lock contention on TCG hot-path, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 02/10] tcg: Pass last_tb by value to tb_find_fast(), Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 01/10] util/qht: Document memory ordering assumptions, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 05/10] tcg: Prepare TB invalidation for lockless TB lookup, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 03/10] tcg: Prepare safe tb_jmp_cache lookup out of tb_lock, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 04/10] tcg: Prepare safe access to tb_flushed out of tb_lock, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 06/10] tcg: set up tb->page_addr before insertion, Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 08/10] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump(),
Paolo Bonzini <=
- [Qemu-devel] [PATCH 10/10] tcg: rename tb_find_physical(), Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 09/10] tcg: Merge tb_find_slow() and tb_find_fast(), Paolo Bonzini, 2016/07/19
- [Qemu-devel] [PATCH 07/10] tcg: cpu-exec: remove tb_lock from the hot-path, Paolo Bonzini, 2016/07/19