From 8d04fb55dec381bc5105cb47f29d918e579e8cbd Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Thu, 23 Feb 2017 18:29:11 +0000 Subject: tcg: drop global lock during TCG code execution MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 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 [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée Reviewed-by: Richard Henderson Reviewed-by: Pranith Kumar [PM: target-arm changes] Acked-by: Peter Maydell --- hw/i386/kvmvapic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'hw/i386/kvmvapic.c') diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c index 7135633863..82a49556af 100644 --- a/hw/i386/kvmvapic.c +++ b/hw/i386/kvmvapic.c @@ -457,8 +457,8 @@ static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip) resume_all_vcpus(); if (!kvm_enabled()) { - /* tb_lock will be reset when cpu_loop_exit_noexc longjmps - * back into the cpu_exec loop. */ + /* Both tb_lock and iothread_mutex will be reset when + * longjmps back into the cpu_exec loop. */ tb_lock(); tb_gen_code(cs, current_pc, current_cs_base, current_flags, 1); cpu_loop_exit_noexc(cs); -- cgit 1.4.1