From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Me5Cg-0002ya-MK for qemu-devel@nongnu.org; Thu, 20 Aug 2009 06:49:10 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Me5Cb-0002vb-S2 for qemu-devel@nongnu.org; Thu, 20 Aug 2009 06:49:10 -0400 Received: from [199.232.76.173] (port=41944 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Me5Cb-0002vO-Ea for qemu-devel@nongnu.org; Thu, 20 Aug 2009 06:49:05 -0400 Received: from cantor.suse.de ([195.135.220.2]:52707 helo=mx1.suse.de) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Me5Ca-0004AM-UR for qemu-devel@nongnu.org; Thu, 20 Aug 2009 06:49:05 -0400 From: Ulrich Hecht Date: Thu, 20 Aug 2009 12:49:03 +0200 Message-Id: <1250765343-9692-1-git-send-email-uli@suse.de> Subject: [Qemu-devel] [PATCH 06/13] linux-user: don't do locking in single-threaded processes List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Riku Voipio Skips setting the tb_lock if a process doesn't have more than one thread, which is usually the case. Results in about 20% performance gain (measured with the s390x target, but the effect should be similar with other targets). Signed-off-by: Ulrich Hecht --- cpu-defs.h | 8 ++++++++ cpu-exec.c | 14 ++++++++++++-- linux-user/syscall.c | 1 + 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/cpu-defs.h b/cpu-defs.h index 5b80b1b..0d0f8d6 100644 --- a/cpu-defs.h +++ b/cpu-defs.h @@ -135,6 +135,13 @@ typedef struct CPUWatchpoint { } CPUWatchpoint; #define CPU_TEMP_BUF_NLONGS 128 + +#ifdef CONFIG_USER_ONLY +#define MULTITHREAD uint32_t multithreaded; +#else +#define MULTITHREAD +#endif + #define CPU_COMMON \ struct TranslationBlock *current_tb; /* currently executing TB */ \ /* soft mmu support */ \ @@ -149,6 +156,7 @@ typedef struct CPUWatchpoint { uint32_t stop; /* Stop request */ \ uint32_t stopped; /* Artificially stopped */ \ uint32_t interrupt_request; \ + MULTITHREAD /* needs locking when accessing TBs */ \ volatile sig_atomic_t exit_request; \ /* The meaning of the MMU modes is defined in the target code. */ \ CPUTLBEntry tlb_table[NB_MMU_MODES][CPU_TLB_SIZE]; \ diff --git a/cpu-exec.c b/cpu-exec.c index f625e57..be2796a 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -219,6 +219,9 @@ int cpu_exec(CPUState *env1) TranslationBlock *tb; uint8_t *tc_ptr; unsigned long next_tb; +#ifdef CONFIG_USER_ONLY + uint32_t multithreaded; +#endif if (cpu_halted(env1) == EXCP_HALTED) return EXCP_HALTED; @@ -604,7 +607,11 @@ int cpu_exec(CPUState *env1) #endif } #endif - spin_lock(&tb_lock); +#ifdef CONFIG_USER_ONLY + multithreaded = env->multithreaded; + if (multithreaded) +#endif + spin_lock(&tb_lock); tb = tb_find_fast(); /* Note: we do it here to avoid a gcc bug on Mac OS X when doing it in tb_find_slow */ @@ -632,7 +639,10 @@ int cpu_exec(CPUState *env1) tb_add_jump((TranslationBlock *)(next_tb & ~3), next_tb & 3, tb); } } - spin_unlock(&tb_lock); +#ifdef CONFIG_USER_ONLY + if (multithreaded) +#endif + spin_unlock(&tb_lock); env->current_tb = tb; /* cpu_interrupt might be called while translating the diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 2ab58e0..6712cb7 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3545,6 +3545,7 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp, ts = qemu_mallocz(sizeof(TaskState) + NEW_STACK_SIZE); init_task_state(ts); new_stack = ts->stack; + env->multithreaded = 1; /* we create a new CPU instance. */ new_env = cpu_copy(env); /* Init regs that differ from the parent. */ -- 1.6.2.1