KONRAD Frederic <fred.kon...@greensocs.com> writes: > Hi Alex, > > Thanks for having pulling all that together! > About this patch the original author was Jan Kiszka > (https://lists.gnu.org/archive/html/qemu-devel/2011-09/msg03323.html) > > This has probably been dropped during a rebase.
I'll amend the author on v2. Jan, The original didn't have a s-o-b tag from you. Are you happy to give one for its current iteration? > > Thanks, > Fred > > Le 18/03/2016 17:18, Alex Bennée a écrit : >> From: KONRAD Frederic <fred.kon...@greensocs.com> >> >> 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. >> >> Message-Id: <1439220437-23957-10-git-send-email-fred.kon...@greensocs.com> >> Signed-off-by: KONRAD Frederic <fred.kon...@greensocs.com> >> [AJB: -smp single-threaded fix, rm old info from commit msg] >> Signed-off-by: Alex Bennée <alex.ben...@linaro.org> >> >> --- >> v1 (ajb): >> - SMP failure now fixed by previous commit >> Changes from Fred Konrad (mttcg-v7 via paolo): >> * Rebase on the current HEAD. >> * Fixes a deadlock in qemu_devices_reset(). >> * Remove the mutex in address_space_* >> --- >> cpu-exec.c | 10 ++++++++++ >> cpus.c | 26 +++----------------------- >> cputlb.c | 4 ++++ >> exec.c | 12 ++++++++++++ >> hw/i386/kvmvapic.c | 3 +++ >> softmmu_template.h | 17 +++++++++++++++++ >> translate-all.c | 11 +++++++++-- >> 7 files changed, 58 insertions(+), 25 deletions(-) >> >> diff --git a/cpu-exec.c b/cpu-exec.c >> index 3572256..76891fd 100644 >> --- a/cpu-exec.c >> +++ b/cpu-exec.c >> @@ -28,6 +28,7 @@ >> #include "qemu/rcu.h" >> #include "exec/tb-hash.h" >> #include "exec/log.h" >> +#include "qemu/main-loop.h" >> #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) >> #include "hw/i386/apic.h" >> #endif >> @@ -449,6 +450,13 @@ int cpu_exec(CPUState *cpu) >> for(;;) { >> interrupt_request = cpu->interrupt_request; >> if (unlikely(interrupt_request)) { >> + /* FIXME: this needs to take the iothread lock. >> + * For this we need to find all places in >> + * cc->cpu_exec_interrupt that can call cpu_loop_exit, >> + * and call qemu_unlock_iothread_mutex() there. Else, >> + * add a flag telling cpu_loop_exit() to unlock it. >> + */ >> + >> if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) { >> /* Mask out external interrupts for this step. */ >> interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK; >> @@ -501,6 +509,7 @@ int cpu_exec(CPUState *cpu) >> the program flow was changed */ >> next_tb = 0; >> } >> + >> } >> if (unlikely(cpu->exit_request >> || replay_has_interrupt())) { >> @@ -618,6 +627,7 @@ int cpu_exec(CPUState *cpu) >> g_assert(env == &x86_cpu->env); >> #endif >> #endif /* buggy compiler */ >> + >> cpu->can_do_io = 1; >> tb_lock_reset(); >> } >> diff --git a/cpus.c b/cpus.c >> index a87fbf9..0e3d5f9 100644 >> --- a/cpus.c >> +++ b/cpus.c >> @@ -911,8 +911,6 @@ static void qemu_kvm_init_cpu_signals(CPUState *cpu) >> #endif /* _WIN32 */ >> >> static QemuMutex qemu_global_mutex; >> -static QemuCond qemu_io_proceeded_cond; >> -static unsigned iothread_requesting_mutex; >> >> static QemuThread io_thread; >> >> @@ -928,7 +926,6 @@ void qemu_init_cpu_loop(void) >> qemu_cond_init(&qemu_cpu_cond); >> qemu_cond_init(&qemu_pause_cond); >> qemu_cond_init(&qemu_work_cond); >> - qemu_cond_init(&qemu_io_proceeded_cond); >> qemu_mutex_init(&qemu_global_mutex); >> >> qemu_thread_get_self(&io_thread); >> @@ -1043,10 +1040,6 @@ static void qemu_tcg_wait_io_event(CPUState *cpu) >> qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex); >> } >> >> - while (iothread_requesting_mutex) { >> - qemu_cond_wait(&qemu_io_proceeded_cond, &qemu_global_mutex); >> - } >> - >> CPU_FOREACH(cpu) { >> qemu_wait_io_event_common(cpu); >> } >> @@ -1314,22 +1307,7 @@ bool qemu_mutex_iothread_locked(void) >> >> void qemu_mutex_lock_iothread(void) >> { >> - atomic_inc(&iothread_requesting_mutex); >> - /* In the simple case there is no need to bump the VCPU thread out of >> - * TCG code execution. >> - */ >> - if (!tcg_enabled() || qemu_in_vcpu_thread() || >> - !first_cpu || !first_cpu->created) { >> - qemu_mutex_lock(&qemu_global_mutex); >> - atomic_dec(&iothread_requesting_mutex); >> - } else { >> - if (qemu_mutex_trylock(&qemu_global_mutex)) { >> - qemu_cpu_kick_no_halt(); >> - qemu_mutex_lock(&qemu_global_mutex); >> - } >> - atomic_dec(&iothread_requesting_mutex); >> - qemu_cond_broadcast(&qemu_io_proceeded_cond); >> - } >> + qemu_mutex_lock(&qemu_global_mutex); >> iothread_locked = true; >> } >> >> @@ -1575,7 +1553,9 @@ static int tcg_cpu_exec(CPUState *cpu) >> cpu->icount_decr.u16.low = decr; >> cpu->icount_extra = count; >> } >> + qemu_mutex_unlock_iothread(); >> ret = cpu_exec(cpu); >> + qemu_mutex_lock_iothread(); >> #ifdef CONFIG_PROFILER >> tcg_time += profile_getclock() - ti; >> #endif >> diff --git a/cputlb.c b/cputlb.c >> index 2f7a166..d607471 100644 >> --- a/cputlb.c >> +++ b/cputlb.c >> @@ -30,6 +30,10 @@ >> #include "exec/ram_addr.h" >> #include "tcg/tcg.h" >> >> +#ifdef CONFIG_SOFTMMU >> +#include "qemu/main-loop.h" >> +#endif >> + >> //#define DEBUG_TLB >> //#define DEBUG_TLB_CHECK >> >> diff --git a/exec.c b/exec.c >> index 402b751..9986d59 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -2113,6 +2113,12 @@ static void check_watchpoint(int offset, int len, >> MemTxAttrs attrs, int flags) >> } >> cpu->watchpoint_hit = wp; >> >> + /* >> + * Unlock iothread mutex before calling cpu_loop_exit >> + * or cpu_resume_from_signal. >> + */ >> + qemu_mutex_unlock_iothread(); >> + >> /* Unlocked by cpu_loop_exit or cpu_resume_from_signal. */ >> tb_lock(); >> tb_check_watchpoint(cpu); >> @@ -2348,8 +2354,14 @@ 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 must 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); >> } >> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c >> index 7c0d542..a0439a8 100644 >> --- a/hw/i386/kvmvapic.c >> +++ b/hw/i386/kvmvapic.c >> @@ -447,6 +447,9 @@ static void patch_instruction(VAPICROMState *s, X86CPU >> *cpu, target_ulong ip) >> resume_all_vcpus(); >> >> if (!kvm_enabled()) { >> + /* Unlock iothread mutex before calling cpu_resume_from_signal. */ >> + qemu_mutex_unlock_iothread(); >> + >> /* Unlocked by cpu_resume_from_signal. */ >> tb_lock(); >> cs->current_tb = NULL; >> diff --git a/softmmu_template.h b/softmmu_template.h >> index 208f808..0b6c609 100644 >> --- a/softmmu_template.h >> +++ b/softmmu_template.h >> @@ -151,6 +151,7 @@ static inline DATA_TYPE glue(io_read, >> SUFFIX)(CPUArchState *env, >> 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; >> cpu->mem_io_pc = retaddr; >> @@ -159,8 +160,15 @@ static inline DATA_TYPE glue(io_read, >> SUFFIX)(CPUArchState *env, >> } >> >> cpu->mem_io_vaddr = addr; >> + if (mr->global_locking) { >> + qemu_mutex_lock_iothread(); >> + locked = true; >> + } >> memory_region_dispatch_read(mr, physaddr, &val, 1 << SHIFT, >> iotlbentry->attrs); >> + if (locked) { >> + qemu_mutex_unlock_iothread(); >> + } >> return val; >> } >> #endif >> @@ -358,6 +366,7 @@ static inline void glue(io_write, SUFFIX)(CPUArchState >> *env, >> 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) { >> @@ -366,8 +375,16 @@ static inline void glue(io_write, SUFFIX)(CPUArchState >> *env, >> >> 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, 1 << SHIFT, >> iotlbentry->attrs); >> + if (locked) { >> + qemu_mutex_unlock_iothread(); >> + } >> } >> >> void helper_le_st_name(CPUArchState *env, target_ulong addr, DATA_TYPE val, >> diff --git a/translate-all.c b/translate-all.c >> index 1aab243..fe1392a 100644 >> --- a/translate-all.c >> +++ b/translate-all.c >> @@ -1221,6 +1221,7 @@ void tb_invalidate_phys_range(tb_page_addr_t start, >> tb_page_addr_t end) >> * this TB. >> * >> * Called with mmap_lock held for user-mode emulation >> + * If called from generated code, iothread mutex must not be held. >> */ >> void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t >> end, >> int is_cpu_write_access) >> @@ -1333,7 +1334,9 @@ void tb_invalidate_phys_page_range(tb_page_addr_t >> start, tb_page_addr_t end, >> } >> >> #ifdef CONFIG_SOFTMMU >> -/* len must be <= 8 and start must be a multiple of len */ >> +/* len must be <= 8 and start must be a multiple of len. >> + * Called via softmmu_template.h, with iothread mutex not held. >> + */ >> void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) >> { >> PageDesc *p; >> @@ -1591,6 +1594,7 @@ static TranslationBlock *tb_find_pc(uintptr_t tc_ptr) >> } >> >> #if !defined(CONFIG_USER_ONLY) >> +/* If called from generated code, iothread mutex must not be held. */ >> void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr) >> { >> ram_addr_t ram_addr; >> @@ -1637,7 +1641,10 @@ void tb_check_watchpoint(CPUState *cpu) >> >> #ifndef CONFIG_USER_ONLY >> /* in deterministic execution mode, instructions doing device I/Os >> - must be at the end of the TB */ >> + * must be at the end of the TB. >> + * >> + * Called by softmmu_template.h, with iothread mutex not held. >> + */ >> void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) >> { >> #if defined(TARGET_MIPS) || defined(TARGET_SH4) -- Alex Bennée