From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shaohua Li <shaohua.li@intel.com>
Subject: Re: the idea for improving the performance of b-tree search
Date: Mon, 18 Oct 2010 10:41:41 +0800
Message-ID: <20101018024141.GA5416@sli10-conroe.sh.intel.com>
References: <4CB57548.7000304@cn.fujitsu.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Chris Mason <chris.mason@oracle.com>,
	Linux Btrfs <linux-btrfs@vger.kernel.org>
To: Miao Xie <miaox@cn.fujitsu.com>
Return-path: <linux-btrfs-owner@vger.kernel.org>
In-Reply-To: <4CB57548.7000304@cn.fujitsu.com>
List-ID: <linux-btrfs.vger.kernel.org>

Hi Miao & Chris,
On Wed, Oct 13, 2010 at 05:00:56PM +0800, Miao Xie wrote:
> When I investigated the performance problem of file creation/deletion, I found
> btrfs spends lots of time in the b-tree search, so I consider whether we can use
> the latest search result in the same transaction or not.
> 
> My idea follows:
> we can add mask or time stamp into b-tree's node and leaf, then we know whether
> the node/leaf is COWed by the other task. If not, we check if the node/leaf of
> the latest search result contains the key that we want to search. By this way,
> we can reuse the latest search result in the same transaction and reduce the CPU
> time spent in the b-tree search.
Does this patch help a little for the tree search?
http://marc.info/?l=linux-btrfs&m=127175532803943&w=2
It doesn't solve all the issues, but in my test, it does help.

Thanks,
Shaohua