From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH v2 0/4] Fix accessed bit tracking
Date: Mon, 07 Jun 2010 16:43:05 +0800 [thread overview]
Message-ID: <4C0CB119.3060903@cn.fujitsu.com> (raw)
In-Reply-To: <1275894659-17656-1-git-send-email-avi@redhat.com>
Avi Kivity wrote:
> The kvm mmu synchronizes shadow ptes using the mmu lock, however the cpu
> will happily ignore the lock when setting the accessed bit. This can cause
> the accessed bit to be lost. Luckily this only results in incorrect page
> selection for swap.
>
Atomic operation is heavy and slow, it hurts performance.
Incorrect page selection for swap also hurts performance.
I think there are very rare competitions happened and cause
the accessed bit to be lost. Since there is no incorrect result
when the accessed bit is lost. Is this problem over concern?
Lai
next prev parent reply other threads:[~2010-06-07 8:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-07 7:10 [PATCH v2 0/4] Fix accessed bit tracking Avi Kivity
2010-06-07 7:10 ` [PATCH v2 1/4] KVM: MMU: Introduce drop_spte() Avi Kivity
2010-06-07 7:10 ` [PATCH v2 2/4] KVM: MMU: Move accessed/dirty bit checks from rmap_remove() to drop_spte() Avi Kivity
2010-06-07 8:16 ` Lai Jiangshan
2010-06-07 9:01 ` Avi Kivity
2010-06-07 7:10 ` [PATCH v2 3/4] KVM: MMU: Atomically check for accessed bit when dropping an spte Avi Kivity
2010-06-08 2:07 ` Xiao Guangrong
2010-06-08 5:51 ` Avi Kivity
2010-06-07 7:10 ` [PATCH v2 4/4] KVM: MMU: Don't drop accessed bit while updating " Avi Kivity
2010-06-07 8:43 ` Lai Jiangshan [this message]
2010-06-07 9:00 ` [PATCH v2 0/4] Fix accessed bit tracking Avi Kivity
2010-06-08 2:35 ` Xiao Guangrong
2010-06-08 5:24 ` Avi Kivity
2010-06-08 6:53 ` Xiao Guangrong
2010-06-08 7:54 ` Avi Kivity
2010-06-08 8:30 ` Xiao Guangrong
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