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Re: [PATCH 27/27] accel/tcg: Precompute curr_cflags into cpu->tcg_cflags
From: |
Alex Bennée |
Subject: |
Re: [PATCH 27/27] accel/tcg: Precompute curr_cflags into cpu->tcg_cflags |
Date: |
Fri, 05 Mar 2021 17:12:21 +0000 |
User-agent: |
mu4e 1.5.8; emacs 28.0.50 |
Richard Henderson <richard.henderson@linaro.org> writes:
> The primary motivation is to remove a dozen insns along
> the fast-path in tb_lookup. As a byproduct, this allows
> us to completely remove parallel_cpus.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> accel/tcg/tcg-accel-ops.h | 1 +
> include/exec/exec-all.h | 7 +------
> include/hw/core/cpu.h | 2 ++
> accel/tcg/cpu-exec.c | 3 ---
> accel/tcg/tcg-accel-ops-mttcg.c | 3 +--
> accel/tcg/tcg-accel-ops-rr.c | 2 +-
> accel/tcg/tcg-accel-ops.c | 8 ++++++++
> accel/tcg/translate-all.c | 4 ----
> linux-user/main.c | 1 +
> linux-user/sh4/signal.c | 8 +++++---
> linux-user/syscall.c | 18 ++++++++++--------
> 11 files changed, 30 insertions(+), 27 deletions(-)
>
> diff --git a/accel/tcg/tcg-accel-ops.h b/accel/tcg/tcg-accel-ops.h
> index 48130006de..6a5fcef889 100644
> --- a/accel/tcg/tcg-accel-ops.h
> +++ b/accel/tcg/tcg-accel-ops.h
> @@ -17,5 +17,6 @@
> void tcg_cpus_destroy(CPUState *cpu);
> int tcg_cpus_exec(CPUState *cpu);
> void tcg_handle_interrupt(CPUState *cpu, int mask);
> +void tcg_cpu_init_cflags(CPUState *cpu, bool parallel);
>
> #endif /* TCG_CPUS_H */
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 75f8c3981a..310f474540 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -510,8 +510,6 @@ struct TranslationBlock {
> uintptr_t jmp_dest[2];
> };
>
> -extern bool parallel_cpus;
> -
> /* Hide the qatomic_read to make code a little easier on the eyes */
> static inline uint32_t tb_cflags(const TranslationBlock *tb)
> {
> @@ -521,10 +519,7 @@ static inline uint32_t tb_cflags(const TranslationBlock
> *tb)
> /* current cflags for hashing/comparison */
> static inline uint32_t curr_cflags(CPUState *cpu)
> {
> - uint32_t cflags = deposit32(0, CF_CLUSTER_SHIFT, 8, cpu->cluster_index);
> - cflags |= parallel_cpus ? CF_PARALLEL : 0;
> - cflags |= icount_enabled() ? CF_USE_ICOUNT : 0;
> - return cflags;
> + return cpu->tcg_cflags;
> }
>
> /* TranslationBlock invalidate API */
> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
> index c005d3dc2d..c68bc3ba8a 100644
> --- a/include/hw/core/cpu.h
> +++ b/include/hw/core/cpu.h
> @@ -282,6 +282,7 @@ struct qemu_work_item;
> * to a cluster this will be UNASSIGNED_CLUSTER_INDEX; otherwise it will
> * be the same as the cluster-id property of the CPU object's
> TYPE_CPU_CLUSTER
> * QOM parent.
> + * @tcg_cflags: Pre-computed cflags for this cpu.
> * @nr_cores: Number of cores within this CPU package.
> * @nr_threads: Number of threads within this CPU.
> * @running: #true if CPU is currently running (lockless).
> @@ -412,6 +413,7 @@ struct CPUState {
> /* TODO Move common fields from CPUArchState here. */
> int cpu_index;
> int cluster_index;
> + uint32_t tcg_cflags;
> uint32_t halted;
> uint32_t can_do_io;
> int32_t exception_index;
> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
> index 931da96c2b..bdfa036ac8 100644
> --- a/accel/tcg/cpu-exec.c
> +++ b/accel/tcg/cpu-exec.c
> @@ -267,8 +267,6 @@ void cpu_exec_step_atomic(CPUState *cpu)
> mmap_unlock();
> }
>
> - /* Since we got here, we know that parallel_cpus must be true. */
> - parallel_cpus = false;
> cpu_exec_enter(cpu);
> /* execute the generated code */
> trace_exec_tb(tb, pc);
> @@ -296,7 +294,6 @@ void cpu_exec_step_atomic(CPUState *cpu)
> * the execution.
> */
> g_assert(cpu_in_exclusive_context(cpu));
> - parallel_cpus = true;
> cpu->running = false;
> end_exclusive();
I don't see where we generate non-parallel aware code. Do we not care
about it anymore? Anyway just an observation:
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
- Re: [PATCH 19/27] tcg/tci: Merge basic arithmetic operations, (continued)
- [PATCH 20/27] tcg/tci: Merge extension operations, Richard Henderson, 2021/03/02
- [PATCH 24/27] accel/tcg: move CF_CLUSTER calculation to curr_cflags, Richard Henderson, 2021/03/02
- [PATCH 23/27] accel/tcg: rename tb_lookup__cpu_state and hoist state extraction, Richard Henderson, 2021/03/02
- [PATCH 21/27] tcg/tci: Merge bswap operations, Richard Henderson, 2021/03/02
- [PATCH 26/27] include/exec: lightly re-arrange TranslationBlock, Richard Henderson, 2021/03/02
- [PATCH 25/27] accel/tcg: drop the use of CF_HASH_MASK and rename params, Richard Henderson, 2021/03/02
- [PATCH 27/27] accel/tcg: Precompute curr_cflags into cpu->tcg_cflags, Richard Henderson, 2021/03/02
- Re: [PATCH 27/27] accel/tcg: Precompute curr_cflags into cpu->tcg_cflags,
Alex Bennée <=
- Re: [PATCH 00/27] tcg patch queue, no-reply, 2021/03/02