From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58195) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNRGx-0007Gm-Kg for qemu-devel@nongnu.org; Wed, 13 Jul 2016 17:00:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bNRGr-0001H2-97 for qemu-devel@nongnu.org; Wed, 13 Jul 2016 17:00:46 -0400 Received: from mail-lf0-x233.google.com ([2a00:1450:4010:c07::233]:33309) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNRGq-0001Gp-QP for qemu-devel@nongnu.org; Wed, 13 Jul 2016 17:00:41 -0400 Received: by mail-lf0-x233.google.com with SMTP id b199so48355556lfe.0 for ; Wed, 13 Jul 2016 14:00:40 -0700 (PDT) From: Sergey Fedorov Date: Thu, 14 Jul 2016 00:00:17 +0300 Message-Id: <1468443622-17368-8-git-send-email-sergey.fedorov@linaro.org> In-Reply-To: <1468443622-17368-1-git-send-email-sergey.fedorov@linaro.org> References: <1468443622-17368-1-git-send-email-sergey.fedorov@linaro.org> Subject: [Qemu-devel] [PATCH v3 07/12] linux-user: Rework exclusive operation mechanism List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: patches@linaro.org, serge.fdrv@gmail.com, MTTCG Devel , =?UTF-8?B?S09OUkFEIEZyw6lkw6lyaWM=?= , Alvise Rigo , "Emilio G. Cota" , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Paolo Bonzini , Richard Henderson , Peter Maydell , Sergey Fedorov , Riku Voipio From: Sergey Fedorov A single variable 'pending_cpus' was used for both counting currently running CPUs and for signalling the pending exclusive operation request. To prepare for supporting operations which requires a quiescent state, like translation buffer flush, it is useful to keep a counter of currently running CPUs always up to date. Use a separate variable 'tcg_pending_threads' to count for currently running CPUs and a separate variable 'exclusive_pending' to indicate that there's an exclusive operation pending. Signed-off-by: Sergey Fedorov Signed-off-by: Sergey Fedorov --- Changes in v2: - Rename 'tcg_pending_cpus' to 'tcg_pending_threads' --- linux-user/main.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/linux-user/main.c b/linux-user/main.c index bdbda693cc5f..5ff0b20bad89 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -112,7 +112,8 @@ static QemuMutex cpu_list_mutex; static QemuMutex exclusive_lock; static QemuCond exclusive_cond; static QemuCond exclusive_resume; -static int pending_cpus; +static bool exclusive_pending; +static int tcg_pending_threads; void qemu_init_cpu_loop(void) { @@ -142,7 +143,8 @@ void fork_end(int child) QTAILQ_REMOVE(&cpus, cpu, node); } } - pending_cpus = 0; + tcg_pending_threads = 0; + exclusive_pending = false; qemu_mutex_init(&exclusive_lock); qemu_mutex_init(&cpu_list_mutex); qemu_cond_init(&exclusive_cond); @@ -159,7 +161,7 @@ void fork_end(int child) must be held. */ static inline void exclusive_idle(void) { - while (pending_cpus) { + while (exclusive_pending) { qemu_cond_wait(&exclusive_resume, &exclusive_lock); } } @@ -173,15 +175,14 @@ static inline void start_exclusive(void) qemu_mutex_lock(&exclusive_lock); exclusive_idle(); - pending_cpus = 1; + exclusive_pending = true; /* Make all other cpus stop executing. */ CPU_FOREACH(other_cpu) { if (other_cpu->running) { - pending_cpus++; cpu_exit(other_cpu); } } - if (pending_cpus > 1) { + while (tcg_pending_threads) { qemu_cond_wait(&exclusive_cond, &exclusive_lock); } } @@ -189,7 +190,7 @@ static inline void start_exclusive(void) /* Finish an exclusive operation. */ static inline void __attribute__((unused)) end_exclusive(void) { - pending_cpus = 0; + exclusive_pending = false; qemu_cond_broadcast(&exclusive_resume); qemu_mutex_unlock(&exclusive_lock); } @@ -200,6 +201,7 @@ static inline void cpu_exec_start(CPUState *cpu) qemu_mutex_lock(&exclusive_lock); exclusive_idle(); cpu->running = true; + tcg_pending_threads++; qemu_mutex_unlock(&exclusive_lock); } @@ -208,11 +210,9 @@ static inline void cpu_exec_end(CPUState *cpu) { qemu_mutex_lock(&exclusive_lock); cpu->running = false; - if (pending_cpus > 1) { - pending_cpus--; - if (pending_cpus == 1) { - qemu_cond_signal(&exclusive_cond); - } + tcg_pending_threads--; + if (!tcg_pending_threads) { + qemu_cond_signal(&exclusive_cond); } exclusive_idle(); qemu_mutex_unlock(&exclusive_lock); -- 1.9.1