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[Qemu-devel] [PATCH v5 17/17] target/arm: Rely on hflags correct in cpu_
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH v5 17/17] target/arm: Rely on hflags correct in cpu_get_tb_cpu_state |
Date: |
Tue, 20 Aug 2019 14:07:20 -0700 |
This is the payoff.
>From perf record -g data of ubuntu 18 boot and shutdown:
BEFORE:
- 23.02% 2.82% qemu-system-aar [.] helper_lookup_tb_ptr
- 20.22% helper_lookup_tb_ptr
+ 10.05% tb_htable_lookup
- 9.13% cpu_get_tb_cpu_state
3.20% aa64_va_parameters_both
0.55% fp_exception_el
- 11.66% 4.74% qemu-system-aar [.] cpu_get_tb_cpu_state
- 6.96% cpu_get_tb_cpu_state
3.63% aa64_va_parameters_both
0.60% fp_exception_el
0.53% sve_exception_el
AFTER:
- 16.40% 3.40% qemu-system-aar [.] helper_lookup_tb_ptr
- 13.03% helper_lookup_tb_ptr
+ 11.19% tb_htable_lookup
0.55% cpu_get_tb_cpu_state
0.98% 0.71% qemu-system-aar [.] cpu_get_tb_cpu_state
0.87% 0.24% qemu-system-aar [.] rebuild_hflags_a64
Before, helper_lookup_tb_ptr is the second hottest function in the
application, consuming almost a quarter of the runtime. Within the
entire execution, cpu_get_tb_cpu_state consumes about 12%.
After, helper_lookup_tb_ptr has dropped to the fourth hottest function,
with consumption dropping to a sixth of the runtime. Within the
entire execution, cpu_get_tb_cpu_state has dropped below 1%, and the
supporting function to rebuild hflags also consumes about 1%.
Assertions are retained for --enable-debug-tcg.
Tested-by: Alex Bennée <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
v2: Retain asserts for future debugging.
---
target/arm/helper.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index d1bf71a260..5e4f996882 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11211,12 +11211,15 @@ void HELPER(rebuild_hflags_a64)(CPUARMState *env, int
el)
void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
target_ulong *cs_base, uint32_t *pflags)
{
- uint32_t flags, pstate_for_ss;
+ uint32_t flags = env->hflags;
+ uint32_t pstate_for_ss;
*cs_base = 0;
- flags = rebuild_hflags_internal(env);
+#ifdef CONFIG_TCG_DEBUG
+ assert(flags == rebuild_hflags_internal(env));
+#endif
- if (is_a64(env)) {
+ if (FIELD_EX32(flags, TBFLAG_ANY, AARCH64_STATE)) {
*pc = env->pc;
if (cpu_isar_feature(aa64_bti, env_archcpu(env))) {
flags = FIELD_DP32(flags, TBFLAG_A64, BTYPE, env->btype);
--
2.17.1
- [Qemu-devel] [PATCH v5 14/17] target/arm: Hoist store to cs_base in cpu_get_tb_cpu_state, (continued)
- [Qemu-devel] [PATCH v5 14/17] target/arm: Hoist store to cs_base in cpu_get_tb_cpu_state, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 12/17] target/arm: Add arm_rebuild_hflags, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 13/17] target/arm: Split out arm_mmu_idx_el, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 16/17] target/arm: Rebuild hflags at EL changes and MSR writes, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 05/17] target/arm: Split out rebuild_hflags_m32, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 07/17] target/arm: Split out rebuild_hflags_a32, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 08/17] target/arm: Split out rebuild_hflags_aprofile, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 10/17] target/arm: Simplify set of PSTATE_SS in cpu_get_tb_cpu_state, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 11/17] target/arm: Hoist computation of TBFLAG_A32.VFPEN, Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 15/17] target/arm: Add HELPER(rebuild_hflags_{a32, a64, m32}), Richard Henderson, 2019/08/20
- [Qemu-devel] [PATCH v5 17/17] target/arm: Rely on hflags correct in cpu_get_tb_cpu_state,
Richard Henderson <=
- Re: [Qemu-devel] [PATCH v5 00/17] target/arm: Reduce overhead of cpu_get_tb_cpu_state, Richard Henderson, 2019/08/20