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| author | Jan Kiszka <jan.kiszka@siemens.com> | 2017-02-23 18:29:11 +0000 |
|---|---|---|
| committer | Alex Bennée <alex.bennee@linaro.org> | 2017-02-24 10:32:45 +0000 |
| commit | 8d04fb55dec381bc5105cb47f29d918e579e8cbd (patch) | |
| tree | 279eb632e33d57c869bae0b70c6261af5d0e854a /exec.c | |
| parent | 791158d93b27f22a17c2ada06621831d54f09a2c (diff) | |
| download | focaccia-qemu-8d04fb55dec381bc5105cb47f29d918e579e8cbd.tar.gz focaccia-qemu-8d04fb55dec381bc5105cb47f29d918e579e8cbd.zip | |
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 'exec.c')
| -rw-r--r-- | exec.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/exec.c b/exec.c index 865a1e8295..3adf2b1861 100644 --- a/exec.c +++ b/exec.c @@ -2134,9 +2134,9 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) } cpu->watchpoint_hit = wp; - /* The tb_lock will be reset when cpu_loop_exit or - * cpu_loop_exit_noexc longjmp back into the cpu_exec - * main loop. + /* Both tb_lock and iothread_mutex will be reset when + * cpu_loop_exit or cpu_loop_exit_noexc longjmp + * back into the cpu_exec main loop. */ tb_lock(); tb_check_watchpoint(cpu); @@ -2371,8 +2371,14 @@ static void io_mem_init(void) memory_region_init_io(&io_mem_rom, NULL, &unassigned_mem_ops, NULL, NULL, UINT64_MAX); memory_region_init_io(&io_mem_unassigned, NULL, &unassigned_mem_ops, NULL, NULL, UINT64_MAX); + + /* io_mem_notdirty calls tb_invalidate_phys_page_fast, + * which can be called without the iothread mutex. + */ memory_region_init_io(&io_mem_notdirty, NULL, ¬dirty_mem_ops, NULL, NULL, UINT64_MAX); + memory_region_clear_global_locking(&io_mem_notdirty); + memory_region_init_io(&io_mem_watch, NULL, &watch_mem_ops, NULL, NULL, UINT64_MAX); } |