[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/3] rcu: run RCU callbacks under the BQL
From: |
Michael Roth |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] rcu: run RCU callbacks under the BQL |
Date: |
Wed, 11 Feb 2015 14:26:49 -0600 |
User-agent: |
alot/0.3.4 |
Quoting Paolo Bonzini (2015-02-11 11:14:31)
> This needs to go away sooner or later, but one complication is the
> complex VFIO data structures that are modified in instance_finalize.
> Take a shortcut for now.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> tests/Makefile | 2 +-
> util/rcu.c | 5 +++++
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/tests/Makefile b/tests/Makefile
> index d5df168..e11bfe7 100644
> --- a/tests/Makefile
> +++ b/tests/Makefile
> @@ -257,7 +257,7 @@ tests/test-x86-cpuid$(EXESUF): tests/test-x86-cpuid.o
> tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o migration/xbzrle.o
> page_cache.o libqemuutil.a
> tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o
> tests/test-int128$(EXESUF): tests/test-int128.o
> -tests/rcutorture$(EXESUF): tests/rcutorture.o libqemuutil.a
> +tests/rcutorture$(EXESUF): tests/rcutorture.o libqemuutil.a libqemustub.a
>
> tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \
> hw/core/qdev.o hw/core/qdev-properties.o hw/core/hotplug.o\
> diff --git a/util/rcu.c b/util/rcu.c
> index 486d7b6..bd73b8e 100644
> --- a/util/rcu.c
> +++ b/util/rcu.c
> @@ -35,6 +35,7 @@
> #include "qemu/rcu.h"
> #include "qemu/atomic.h"
> #include "qemu/thread.h"
> +#include "qemu/main-loop.h"
>
> /*
> * Global grace period counter. Bit 0 is always one in rcu_gp_ctr.
> @@ -237,20 +238,24 @@ static void *call_rcu_thread(void *opaque)
>
> atomic_sub(&rcu_call_count, n);
> synchronize_rcu();
> + qemu_mutex_lock_iothread();
> while (n > 0) {
> node = try_dequeue();
> while (!node) {
> + qemu_mutex_unlock_iothread();
> qemu_event_reset(&rcu_call_ready_event);
> node = try_dequeue();
> if (!node) {
> qemu_event_wait(&rcu_call_ready_event);
> node = try_dequeue();
> }
> + qemu_mutex_lock_iothread();
> }
>
> n--;
> node->func(node);
Not sure I understand the reasoning for lock/unlock beyond just guarding
the ->func() call, what else are we serializing?
> }
> + qemu_mutex_unlock_iothread();
> }
> abort();
> }
> --
> 1.8.3.1