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Re: [Qemu-devel] [PATCH v3 11/11] tcg: Merge tb_find_slow() and tb_find_
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH v3 11/11] tcg: Merge tb_find_slow() and tb_find_fast() |
Date: |
Thu, 14 Jul 2016 14:02:43 +0100 |
User-agent: |
mu4e 0.9.17; emacs 25.0.95.9 |
Sergey Fedorov <address@hidden> writes:
> From: Sergey Fedorov <address@hidden>
>
> These functions are not too big and can be merged together. This makes
> locking scheme more clear and easier to follow.
>
> Signed-off-by: Sergey Fedorov <address@hidden>
> Signed-off-by: Sergey Fedorov <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
c.f. comments on 10/11.
> ---
> cpu-exec.c | 72
> ++++++++++++++++++++++++++------------------------------------
> 1 file changed, 30 insertions(+), 42 deletions(-)
>
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 22c672fe03fd..6b01e8ceb0e8 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -278,45 +278,9 @@ static TranslationBlock *tb_find_physical(CPUState *cpu,
> return qht_lookup(&tcg_ctx.tb_ctx.htable, tb_cmp, &desc, h);
> }
>
> -static TranslationBlock *tb_find_slow(CPUState *cpu,
> - target_ulong pc,
> - target_ulong cs_base,
> - uint32_t flags,
> - bool *have_tb_lock)
> -{
> - TranslationBlock *tb;
> -
> - tb = tb_find_physical(cpu, pc, cs_base, flags);
> - if (!tb) {
> -
> - /* mmap_lock is needed by tb_gen_code, and mmap_lock must be
> - * taken outside tb_lock. As system emulation is currently
> - * single threaded the locks are NOPs.
> - */
> - 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.
> - */
> - tb = tb_find_physical(cpu, pc, cs_base, flags);
> - if (!tb) {
> - /* if no translated code available, then translate it now */
> - tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
> - }
> -
> - mmap_unlock();
> - }
> -
> - /* We add the TB in the virtual pc hash table for the fast lookup */
> - atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
> - return tb;
> -}
> -
> -static inline TranslationBlock *tb_find_fast(CPUState *cpu,
> - TranslationBlock *last_tb,
> - int tb_exit)
> +static inline TranslationBlock *tb_find(CPUState *cpu,
> + TranslationBlock *last_tb,
> + int tb_exit)
> {
> CPUArchState *env = (CPUArchState *)cpu->env_ptr;
> TranslationBlock *tb;
> @@ -331,7 +295,31 @@ 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, &have_tb_lock);
> + tb = tb_find_physical(cpu, pc, cs_base, flags);
> + if (!tb) {
> +
> + /* mmap_lock is needed by tb_gen_code, and mmap_lock must be
> + * taken outside tb_lock. As system emulation is currently
> + * single threaded the locks are NOPs.
> + */
> + 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.
> + */
> + tb = tb_find_physical(cpu, pc, cs_base, flags);
> + if (!tb) {
> + /* if no translated code available, then translate it now */
> + tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
> + }
> +
> + mmap_unlock();
> + }
> +
> + /* We add the TB in the virtual pc hash table for the fast lookup */
> + atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
> }
> #ifndef CONFIG_USER_ONLY
> /* We don't take care of direct jumps when address mapping changes in
> @@ -436,7 +424,7 @@ static inline bool cpu_handle_exception(CPUState *cpu,
> int *ret)
> } else if (replay_has_exception()
> && cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
> /* try to cause an exception pending in the log */
> - cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, NULL, 0), true);
> + cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0), true);
> *ret = -1;
> return true;
> #endif
> @@ -620,7 +608,7 @@ int cpu_exec(CPUState *cpu)
> atomic_mb_set(&cpu->tb_flushed, false); /* reset before first TB
> lookup */
> for(;;) {
> cpu_handle_interrupt(cpu, &last_tb);
> - tb = tb_find_fast(cpu, last_tb, tb_exit);
> + tb = tb_find(cpu, last_tb, tb_exit);
> cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc);
> /* Try to align the host and virtual clocks
> if the guest is in advance */
--
Alex Bennée
[Qemu-devel] [PATCH v3 11/11] tcg: Merge tb_find_slow() and tb_find_fast(), Sergey Fedorov, 2016/07/12
- Re: [Qemu-devel] [PATCH v3 11/11] tcg: Merge tb_find_slow() and tb_find_fast(),
Alex Bennée <=
[Qemu-devel] [PATCH v3 10/11] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump(), Sergey Fedorov, 2016/07/12
Re: [Qemu-devel] [PATCH v3 00/11] Reduce lock contention on TCG hot-path, Paolo Bonzini, 2016/07/13
Re: [Qemu-devel] [PATCH v3 00/11] Reduce lock contention on TCG hot-path, Sergey Fedorov, 2016/07/13
Re: [Qemu-devel] [PATCH v3 00/11] Reduce lock contention on TCG hot-path, Alex Bennée, 2016/07/14