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[97.113.165.157]) by smtp.gmail.com with ESMTPSA id e63sm22917171pfb.18.2017.06.19.11.18.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Jun 2017 11:18:51 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Mon, 19 Jun 2017 11:18:36 -0700 Message-Id: <20170619181839.25249-10-rth@twiddle.net> X-Mailer: git-send-email 2.9.4 In-Reply-To: <20170619181839.25249-1-rth@twiddle.net> References: <20170619181839.25249-1-rth@twiddle.net> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:400e:c00::244 Subject: [Qemu-devel] [PULL 09/12] tcg: Increase hit rate of lookup_tb_ptr X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, "Emilio G . Cota" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP We can call tb_htable_lookup even when the tb_jmp_cache is completely empty. Therefore, un-nest most of the code dependent on tb != NULL from the read from the cache. This improves the hit rate of lookup_tb_ptr; for instance, when booting and immediately shutting down debian-arm, the hit rate improves from 93.2% to 99.4%. Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- tcg-runtime.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/tcg-runtime.c b/tcg-runtime.c index 7fa90ce..ec3a34e 100644 --- a/tcg-runtime.c +++ b/tcg-runtime.c @@ -149,23 +149,23 @@ void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr) CPUState *cpu = ENV_GET_CPU(env); TranslationBlock *tb; target_ulong cs_base, pc; - uint32_t flags; - - tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)]); - if (likely(tb)) { - cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); - if (likely(tb->pc == addr && tb->cs_base == cs_base && - tb->flags == flags)) { - goto found; - } + uint32_t flags, addr_hash; + + addr_hash = tb_jmp_cache_hash_func(addr); + tb = atomic_rcu_read(&cpu->tb_jmp_cache[addr_hash]); + cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); + + if (unlikely(!(tb + && tb->pc == addr + && tb->cs_base == cs_base + && tb->flags == flags))) { tb = tb_htable_lookup(cpu, addr, cs_base, flags); - if (likely(tb)) { - atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)], tb); - goto found; + if (!tb) { + return tcg_ctx.code_gen_epilogue; } + atomic_set(&cpu->tb_jmp_cache[addr_hash], tb); } - return tcg_ctx.code_gen_epilogue; - found: + qemu_log_mask_and_addr(CPU_LOG_EXEC, addr, "Chain %p [%d: " TARGET_FMT_lx "] %s\n", tb->tc_ptr, cpu->cpu_index, addr,