From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 27 May 2015 01:39:37 +0000 (+0930)
Subject: module: Optimize __module_address() using a latched RB-tree
X-Git-Tag: omap-for-v4.2/fixes-rc1^2~63^2~17
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=93c2e105f6bcee231c951ba0e56e84505c4b0483;p=pandora-kernel.git

module: Optimize __module_address() using a latched RB-tree

Currently __module_address() is using a linear search through all
modules in order to find the module corresponding to the provided
address. With a lot of modules this can take a lot of time.

One of the users of this is kernel_text_address() which is employed
in many stack unwinders; which in turn are used by perf-callchain and
ftrace (possibly from NMI context).

So by optimizing __module_address() we optimize many stack unwinders
which are used by both perf and tracing in performance sensitive code.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---

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