linux-kernel - Re: [PATCH] Improve scalability of epoll

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Message-ID: <4783A41B.1090100@cosmosbay.com>
Date:	Tue, 08 Jan 2008 17:26:03 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Improve scalability of epoll_ctl

Changli Gao a écrit :
> Replace the epitem rbtree with a dynamic array to get the constant insertion/deletion/modification time of the file descriptors. Reuse the size argument of epoll_create, however the size must be smaller than the max file descriptor number: ether the resource limitation or the compiling time limitation.
>
>   
Hum, you should read this :

http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.7-rc3/2.6.7-rc3-mm2/broken-out/epoll-uses-rbtrees.patch


Your patch is a revert of this change, it probably wont be accepted.

epoll_ctl() is scalable, since it's O(log2(N)) : With 1 millions files
descriptors, that means less than 20 nodes to lookup in the tree.

In what situation do you think epoll_ctl() performance is bad ?





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