From: Avi Kivity <avi@redhat.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>,
Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [PATCH 4/7] KVM: sort memslots and use binary search to search the right slot
Date: Tue, 22 Feb 2011 16:25:23 +0200 [thread overview]
Message-ID: <4D63C753.3030906@redhat.com> (raw)
In-Reply-To: <4D636FE8.8000505@cn.fujitsu.com>
On 02/22/2011 10:12 AM, Xiao Guangrong wrote:
> Sort memslots then search the slot with binary search to speed up the
> slot searching
>
I'm not sure if a binary search is the right algorithm here. It
introduces a lot of branches which may be mispredicted.
Options we've discussed are:
- Sort slots by size, use linear search (so the largest slots are found
quickly)
- Weighted balanced tree
http://en.wikipedia.org/wiki/Weight-balanced_tree, use weight == slot size
Both options still make the miss case (mmio) slow. We could cache the
result of a miss in an spte by using a reserved bit, and checking the
page fault error code (or seeing if we get an ept violation or ept
misconfiguration), so if we get repeated mmio on a page, we don't need
to search the slot list/tree.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-02-22 14:25 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-22 8:08 [PATCH 0/7] KVM: optimize memslots searching and cache GPN to GFN Xiao Guangrong
2011-02-22 8:09 ` [PATCH 1/7] KVM: cleanup memslot_id function Xiao Guangrong
2011-02-22 8:10 ` [PATCH 2/7] KVM: introduce KVM_MEM_SLOTS_NUM macro Xiao Guangrong
2011-02-22 8:11 ` [PATCH 1/3] KVM: introduce memslots_updated function Xiao Guangrong
2011-02-22 8:12 ` [PATCH 4/7] KVM: sort memslots and use binary search to search the right slot Xiao Guangrong
2011-02-22 14:25 ` Avi Kivity [this message]
2011-02-22 14:54 ` Alex Williamson
2011-02-22 18:54 ` [RFC PATCH 0/3] Weight-balanced binary tree + KVM growable memory slots using wbtree Alex Williamson
2011-02-22 18:55 ` [RFC PATCH 1/3] Weight-balanced tree Alex Williamson
2011-02-23 13:09 ` Avi Kivity
2011-02-23 17:02 ` Alex Williamson
2011-02-23 17:08 ` Avi Kivity
2011-02-23 20:19 ` Alex Williamson
2011-02-24 23:04 ` Andrew Morton
2011-02-22 18:55 ` [RFC PATCH 2/3] kvm: Allow memory slot array to grow on demand Alex Williamson
2011-02-24 10:39 ` Avi Kivity
2011-02-24 18:08 ` Alex Williamson
2011-02-27 9:44 ` Avi Kivity
2011-02-22 18:55 ` [RFC PATCH 3/3] kvm: Use weight-balanced tree for memory slot management Alex Williamson
2011-02-22 18:59 ` [RFC PATCH 0/3] Weight-balanced binary tree + KVM growable memory slots using wbtree Alex Williamson
2011-02-23 1:56 ` Alex Williamson
2011-02-23 13:12 ` Avi Kivity
2011-02-23 18:06 ` Alex Williamson
2011-02-23 19:28 ` Alex Williamson
2011-02-24 10:06 ` Avi Kivity
2011-02-24 17:35 ` Alex Williamson
2011-02-27 9:54 ` Avi Kivity
2011-02-28 23:04 ` Alex Williamson
2011-03-01 15:03 ` Avi Kivity
2011-03-01 18:20 ` Alex Williamson
2011-03-02 13:31 ` Avi Kivity
2011-03-01 19:47 ` Marcelo Tosatti
2011-03-02 13:34 ` Avi Kivity
2011-02-24 10:04 ` Avi Kivity
2011-02-23 1:30 ` [PATCH 4/7] KVM: sort memslots and use binary search to search the right slot Xiao Guangrong
2011-02-22 8:13 ` [PATCH 5/7] KVM: cache the last used slot Xiao Guangrong
2011-02-22 14:26 ` Avi Kivity
2011-02-22 8:15 ` [PATCH 6/7] KVM: cleanup traversal used slots Xiao Guangrong
2011-02-22 8:16 ` [PATCH 7/7] KVM: MMU: cache guest page number to guest frame number Xiao Guangrong
2011-02-22 14:32 ` Avi Kivity
2011-02-23 1:38 ` Xiao Guangrong
2011-02-23 9:28 ` Avi Kivity
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