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 --- cputlb.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'cputlb.c') diff --git a/cputlb.c b/cputlb.c index 6c39927455..1cc9d9da51 100644 --- a/cputlb.c +++ b/cputlb.c @@ -18,6 +18,7 @@ */ #include "qemu/osdep.h" +#include "qemu/main-loop.h" #include "cpu.h" #include "exec/exec-all.h" #include "exec/memory.h" @@ -495,6 +496,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry, hwaddr physaddr = iotlbentry->addr; MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs); uint64_t val; + bool locked = false; physaddr = (physaddr & TARGET_PAGE_MASK) + addr; cpu->mem_io_pc = retaddr; @@ -503,7 +505,16 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry, } cpu->mem_io_vaddr = addr; + + if (mr->global_locking) { + qemu_mutex_lock_iothread(); + locked = true; + } memory_region_dispatch_read(mr, physaddr, &val, size, iotlbentry->attrs); + if (locked) { + qemu_mutex_unlock_iothread(); + } + return val; } @@ -514,15 +525,23 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry, CPUState *cpu = ENV_GET_CPU(env); hwaddr physaddr = iotlbentry->addr; MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs); + bool locked = false; physaddr = (physaddr & TARGET_PAGE_MASK) + addr; if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) { cpu_io_recompile(cpu, retaddr); } - cpu->mem_io_vaddr = addr; cpu->mem_io_pc = retaddr; + + if (mr->global_locking) { + qemu_mutex_lock_iothread(); + locked = true; + } memory_region_dispatch_write(mr, physaddr, val, size, iotlbentry->attrs); + if (locked) { + qemu_mutex_unlock_iothread(); + } } /* Return true if ADDR is present in the victim tlb, and has been copied -- cgit 1.4.1