[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v5 07/13] linux-user: Rework exclusive operation mec
From: |
Alex Bennée |
Subject: |
[Qemu-devel] [PATCH v5 07/13] linux-user: Rework exclusive operation mechanism |
Date: |
Tue, 2 Aug 2016 18:27:38 +0100 |
From: Sergey Fedorov <address@hidden>
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 <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
Signed-off-by: Alex Bennée <address@hidden>
---
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 c80caeb..60ca69f 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -115,7 +115,8 @@ 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)
{
@@ -145,7 +146,8 @@ 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);
@@ -162,7 +164,7 @@ 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);
}
}
@@ -176,15 +178,14 @@ 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);
}
}
@@ -192,7 +193,7 @@ 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);
}
@@ -203,6 +204,7 @@ 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);
}
@@ -211,11 +213,9 @@ 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);
--
2.7.4
- [Qemu-devel] [PATCH v5 00/13] cpu-exec: Safe work in quiescent state, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 01/13] atomic: introduce atomic_dec_fetch., Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 05/13] cpus: Rename flush_queued_work(), Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 08/13] linux-user: Add qemu_cpu_is_self() and qemu_cpu_kick(), Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 02/13] cpus: pass CPUState to run_on_cpu helpers, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 04/13] cpus: Wrap mutex used to protect CPU work, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 03/13] cpus: Move common code out of {async_, }run_on_cpu(), Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 07/13] linux-user: Rework exclusive operation mechanism,
Alex Bennée <=
- [Qemu-devel] [PATCH v5 06/13] linux-user: Use QemuMutex and QemuCond, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 12/13] tcg: Make tb_flush() thread safe, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 10/13] bsd-user: Support CPU work queue, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 13/13] cpu-exec: replace cpu->queued_work with GArray, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 09/13] linux-user: Support CPU work queue, Alex Bennée, 2016/08/02
- [Qemu-devel] [PATCH v5 11/13] cpu-exec-common: Introduce async_safe_run_on_cpu(), Alex Bennée, 2016/08/02