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Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping t
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads |
Date: |
Fri, 19 Jan 2018 15:05:55 +0300 |
> From: Paolo Bonzini [mailto:address@hidden
> On 19/01/2018 09:44, Pavel Dovgalyuk wrote:
> > while (all_cpu_threads_idle()) {
> > + qemu_mutex_lock_iothread();
> > stop_tcg_kick_timer();
> > qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
> > + qemu_mutex_unlock_iothread();
> > }
>
> cpu_has_work cannot be called outside BQL yet. You first need to access
> cpu->interrupt_request with atomics.
>
> In general, testing the condition outside the mutex is a very dangerous
> pattern (and I'm usually the one who enjoys dangerous patterns).
It means, that I'll have to fix all the has_work function to avoid races,
because x86_cpu_has_work may have them?
static bool x86_cpu_has_work(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
return ((cs->interrupt_request & (CPU_INTERRUPT_HARD |
CPU_INTERRUPT_POLL)) &&
(env->eflags & IF_MASK)) ||
(cs->interrupt_request & (CPU_INTERRUPT_NMI |
CPU_INTERRUPT_INIT |
CPU_INTERRUPT_SIPI |
CPU_INTERRUPT_MCE)) ||
((cs->interrupt_request & CPU_INTERRUPT_SMI) &&
!(env->hflags & HF_SMM_MASK));
}
Pavel Dovgalyuk
- [Qemu-devel] [RFC PATCH v4 08/23] replay: added replay log format description, (continued)
- [Qemu-devel] [RFC PATCH v4 08/23] replay: added replay log format description, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 09/23] replay: make safe vmstop at record/replay, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 10/23] replay: save prior value of the host clock, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 11/23] target/arm/arm-powertctl: drop BQL assertions, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 12/23] cpus: push BQL lock to qemu_*_wait_io_event, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 14/23] replay/replay.c: bump REPLAY_VERSION again, Pavel Dovgalyuk, 2018/01/19
- [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Pavel Dovgalyuk, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Paolo Bonzini, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads,
Pavel Dovgalyuk <=
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Paolo Bonzini, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Pavel Dovgalyuk, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Paolo Bonzini, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Pavel Dovgalyuk, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Pavel Dovgalyuk, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Paolo Bonzini, 2018/01/19
- Re: [Qemu-devel] [RFC PATCH v4 13/23] cpus: only take BQL for sleeping threads, Pavel Dovgalyuk, 2018/01/22
[Qemu-devel] [RFC PATCH v4 15/23] replay/replay-internal.c: track holding of replay_lock, Pavel Dovgalyuk, 2018/01/19
[Qemu-devel] [RFC PATCH v4 16/23] replay: make locking visible outside replay code, Pavel Dovgalyuk, 2018/01/19
[Qemu-devel] [RFC PATCH v4 17/23] replay: push replay_mutex_lock up the call tree, Pavel Dovgalyuk, 2018/01/19