From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
Subject: Re: 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
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To: Avi Kivity <avi@redhat.com>
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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