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[Qemu-devel] [PATCH v4 10/12] tcg: Avoid bouncing tb_lock between tb_gen
From: |
Sergey Fedorov |
Subject: |
[Qemu-devel] [PATCH v4 10/12] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump() |
Date: |
Fri, 15 Jul 2016 20:58:50 +0300 |
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>
---
cpu-exec.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index bbaed5bb1978..073d783398f3 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -281,7 +281,8 @@ 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;
@@ -294,6 +295,7 @@ 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.
@@ -304,7 +306,6 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
}
- tb_unlock();
mmap_unlock();
}
@@ -321,6 +322,7 @@ 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
@@ -329,8 +331,8 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu,
tb = atomic_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]);
if (unlikely(!tb || atomic_read(&tb->pc) != pc ||
atomic_read(&tb->cs_base) != cs_base ||
- atomic_read(&b->flags) != flags)) {
- tb = tb_find_slow(cpu, pc, cs_base, flags);
+ atomic_read(&tb->flags) != 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_is_invalid(tb)) {
tb_add_jump(last_tb, tb_exit, tb);
}
+ }
+ if (have_tb_lock) {
tb_unlock();
}
return tb;
--
2.9.1
- [Qemu-devel] [PATCH v4 00/12] Reduce lock contention on TCG hot-path, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 02/12] tcg: Pass last_tb by value to tb_find_fast(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 03/12] tcg: Prepare safe tb_jmp_cache lookup out of tb_lock, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 01/12] util/qht: Document memory ordering assumptions, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 04/12] tcg: Prepare safe access to tb_flushed out of tb_lock, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 08/12] tcg: set up tb->page_addr before insertion, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 07/12] tcg: Prepare TB invalidation for lockless TB lookup, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 05/12] target-i386: Remove redundant HF_SOFTMMU_MASK, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 06/12] tcg: Introduce tb_mark_invalid() and tb_is_invalid(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 09/12] tcg: cpu-exec: remove tb_lock from the hot-path, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 10/12] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump(),
Sergey Fedorov <=
- [Qemu-devel] [PATCH v4 12/12] tcg: rename tb_find_physical(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 11/12] tcg: Merge tb_find_slow() and tb_find_fast(), Sergey Fedorov, 2016/07/15
- Re: [Qemu-devel] [PATCH v4 00/12] Reduce lock contention on TCG hot-path, Paolo Bonzini, 2016/07/16