From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
To: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>, Avi Kivity <avi@redhat.com>,
mtosatti@redhat.com, kvm@vger.kernel.org,
yoshikawa.takuya@oss.ntt.co.jp
Subject: Re: [RFC PATCH 3/3] KVM: MMU: Optimize guest page table walk
Date: Fri, 29 Apr 2011 15:30:58 +0900 [thread overview]
Message-ID: <20110429153058.acbc1e63.takuya.yoshikawa@gmail.com> (raw)
In-Reply-To: <20110429143808.29c51c6a.takuya.yoshikawa@gmail.com>
On Fri, 29 Apr 2011 14:38:08 +0900
Takuya Yoshikawa <takuya.yoshikawa@gmail.com> wrote:
> On Thu, 28 Apr 2011 19:46:00 -0700
> Andi Kleen <andi@firstfloor.org> wrote:
>
> > Avi Kivity <avi@redhat.com> writes:
> > >
> > > Good optimization. copy_from_user() really isn't optimized for short
> > > buffers, I expect much of the improvement comes from that.
> >
> > Actually it is equivalent to get_user for the lenghts supported by
> > get_user, assuming you pass in a constant length. You probably do not.
> >
> > -Andi
>
>
> Weird, I actually measured some changes even after dropping other parts
> than get_user() usage.
>
> Only I can guess for that reason is the reduction of some function calls
> by inlining some functions.
A bit to clarify.
Original path:
kvm_read_guest_page_mmu()
kvm_read_guest_page()
copy_from_user()
Takuya
next prev parent reply other threads:[~2011-04-29 6:31 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-18 18:32 [PATCH 1/3] KVM: Introduce a helper to check if gfn is in memslot Takuya Yoshikawa
2011-04-18 18:34 ` [PATCH 2/3] KVM: MMU: Introduce a helper to read guest pte Takuya Yoshikawa
2011-04-20 9:07 ` Avi Kivity
2011-04-20 9:35 ` Roedel, Joerg
2011-04-20 10:05 ` Avi Kivity
2011-04-20 11:06 ` Roedel, Joerg
2011-04-20 11:18 ` Avi Kivity
2011-04-20 13:33 ` [PATCH] KVM: MMU: Make cmpxchg_gpte aware of nesting too Roedel, Joerg
2011-04-21 1:02 ` Takuya Yoshikawa
2011-04-21 8:11 ` Avi Kivity
2011-04-21 1:07 ` [PATCH 2/3] KVM: MMU: Introduce a helper to read guest pte Takuya Yoshikawa
2011-04-18 18:38 ` [RFC PATCH 3/3] KVM: MMU: Optimize guest page table walk Takuya Yoshikawa
2011-04-18 18:52 ` Joerg Roedel
2011-04-19 1:24 ` Takuya Yoshikawa
2011-04-19 6:20 ` Joerg Roedel
2011-04-19 1:42 ` Xiao Guangrong
2011-04-19 3:47 ` Takuya Yoshikawa
2011-04-20 9:09 ` Avi Kivity
2011-04-20 9:02 ` Avi Kivity
2011-04-29 2:46 ` Andi Kleen
2011-04-29 5:38 ` Takuya Yoshikawa
2011-04-29 6:30 ` Takuya Yoshikawa [this message]
2011-04-29 6:59 ` Andi Kleen
2011-04-29 13:51 ` Takuya Yoshikawa
2011-04-29 16:05 ` Andi Kleen
2011-05-01 13:32 ` Avi Kivity
2011-05-01 20:51 ` Andi Kleen
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