From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
To: Avi Kivity <avi@redhat.com>
Cc: yoshikawa.takuya@oss.ntt.co.jp, mtosatti@redhat.com,
qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Heavy memory_region_get_dirty() -- Re: [PATCH 0/1 v2] KVM: Alleviate mmu_lock contention during dirty logging
Date: Wed, 2 May 2012 23:20:50 +0900 [thread overview]
Message-ID: <20120502232050.f9effe55ba1eb02720982b36@gmail.com> (raw)
In-Reply-To: <4FA11BA3.2000605@redhat.com>
On Wed, 02 May 2012 14:33:55 +0300
Avi Kivity <avi@redhat.com> wrote:
> > =============================
> > perf top -t ${QEMU_TID}
> > =============================
> > 51.52% qemu-system-x86_64 [.] memory_region_get_dirty
> > 16.73% qemu-system-x86_64 [.] ram_save_remaining
> >
>
> memory_region_get_dirty() is called from ram_save_remaining(). Looks
> like quadratic behaviour here: we send a few pages in
> ram_save_remaining(), then walk the entire dirty bitmap to calculate
> expected_time().
>
> We should probably calculate expected_time once per iteration.
There seems to be many unnecessary/repeated calculations.
Not restricted to this expected_time one.
Takuya
prev parent reply other threads:[~2012-05-02 14:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120428190544.7dc2bfd281054c1fcac5a14e@gmail.com>
2012-05-02 11:24 ` [Qemu-devel] Heavy memory_region_get_dirty() -- Re: [PATCH 0/1 v2] KVM: Alleviate mmu_lock contention during dirty logging Takuya Yoshikawa
2012-05-02 11:33 ` Avi Kivity
2012-05-02 14:20 ` Takuya Yoshikawa [this message]
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