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From: Avi Kivity <avi@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org
Subject: Re: [patch 03/10] KVM: switch dirty_log to mmu_lock protection
Date: Tue, 22 Sep 2009 09:37:51 +0300
Message-ID: <4AB870BF.4090905@redhat.com> (raw)
In-Reply-To: <20090921234124.205345161@amt.cnet>

On 09/22/2009 02:37 AM, Marcelo Tosatti wrote:
> get_dirty_log vs mark_page_dirty need to be mutually exclusive. Switch
> to mmu_lock protection.
>
>    

I'm not sure all archs use mmu_lock.  Also, I'm unhappy about 
introducing more use (especially as it's often unnecessary, if dirty 
logging is turned off for the slot for example).

I think you can use rcu for this as well.  When you read the log, 
allocate a new empty bitmap, switch the memslots pointer to include it, 
and synchronize_srcu().  Now we are certain everyone is using the new 
bitmap we can copy the old one to usespace and delete it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-21 23:37 [patch 00/10] RFC: switch vcpu context to use SRCU Marcelo Tosatti
2009-09-21 23:37 ` [patch 01/10] KVM: modify memslots layout in struct kvm Marcelo Tosatti
2009-09-21 23:37 ` [patch 02/10] KVM: modify alias layout in x86s struct kvm_arch Marcelo Tosatti
2009-09-21 23:37 ` [patch 03/10] KVM: switch dirty_log to mmu_lock protection Marcelo Tosatti
2009-09-22  6:37   ` Avi Kivity [this message]
2009-09-22 12:44     ` Marcelo Tosatti
2009-09-22 12:52       ` Avi Kivity
2009-09-21 23:37 ` [patch 04/10] KVM: split kvm_arch_set_memory_region into prepare and commit Marcelo Tosatti
2009-09-22  6:40   ` Avi Kivity
2009-09-21 23:37 ` [patch 05/10] KVM: introduce gfn_to_pfn_memslot Marcelo Tosatti
2009-09-21 23:37 ` [patch 06/10] KVM: use gfn_to_pfn_memslot in kvm_iommu_map_pages Marcelo Tosatti
2009-09-21 23:37 ` [patch 07/10] KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update Marcelo Tosatti
2009-09-22  6:59   ` Avi Kivity
2009-09-22 16:16     ` Marcelo Tosatti
2009-09-22 10:40   ` Fernando Carrijo
2009-09-22 12:55     ` Marcelo Tosatti
2009-09-24 14:06   ` Marcelo Tosatti
2009-09-24 17:28     ` Paul E. McKenney
2009-09-24 18:05       ` Marcelo Tosatti
2009-09-25 15:05       ` Avi Kivity
2009-09-21 23:37 ` [patch 08/10] KVM: x86: switch kvm_set_memory_alias " Marcelo Tosatti
2009-09-22  7:04   ` Avi Kivity
2009-09-21 23:37 ` [patch 09/10] KVM: convert io_bus to SRCU Marcelo Tosatti
2009-09-21 23:37 ` [patch 10/10] KVM: switch vcpu context to use SRCU Marcelo Tosatti
2009-09-22  7:07   ` Avi Kivity
2009-09-22  7:09 ` [patch 00/10] RFC: " Avi Kivity

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