aboutsummaryrefslogtreecommitdiff
path: root/qom/cpu.c
diff options
context:
space:
mode:
authorJan Kiszka <jan.kiszka@siemens.com>2017-02-23 18:29:11 +0000
committerAlex Bennée <alex.bennee@linaro.org>2017-02-24 10:32:45 +0000
commit8d04fb55dec381bc5105cb47f29d918e579e8cbd (patch)
tree279eb632e33d57c869bae0b70c6261af5d0e854a /qom/cpu.c
parent791158d93b27f22a17c2ada06621831d54f09a2c (diff)
tcg: drop global lock during TCG code execution
This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'qom/cpu.c')
-rw-r--r--qom/cpu.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/qom/cpu.c b/qom/cpu.c
index ed87c50cea..58784bcbea 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -113,9 +113,19 @@ static void cpu_common_get_memory_mapping(CPUState *cpu,
error_setg(errp, "Obtaining memory mappings is unsupported on this CPU.");
}
+/* Resetting the IRQ comes from across the code base so we take the
+ * BQL here if we need to. cpu_interrupt assumes it is held.*/
void cpu_reset_interrupt(CPUState *cpu, int mask)
{
+ bool need_lock = !qemu_mutex_iothread_locked();
+
+ if (need_lock) {
+ qemu_mutex_lock_iothread();
+ }
cpu->interrupt_request &= ~mask;
+ if (need_lock) {
+ qemu_mutex_unlock_iothread();
+ }
}
void cpu_exit(CPUState *cpu)