From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamie@jamieiles.com (Jamie Iles) Date: Thu, 11 Nov 2010 09:17:34 +0000 Subject: [Questions] How to run 'perf top' on ARM to profile kernel functions with modules loaded In-Reply-To: References: Message-ID: <20101111091733.GA2929@pulham.picochip.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Nov 11, 2010 at 03:52:07PM +0800, Ming Lei wrote: > 2010/11/11 Ming Lei : > > Hi, > > > > 'perf top' can't display any functions when modules are loaded on ARM. > > Sorry, should be can't display any kernel functions when modules are loaded > on ARM. I've noticed this myself and I spent a bit of time looking into it last week but didn't get too far. I did wonder if it was something to do with the map fixups after loading the modules. If you look at the raw events after a perf record with 'perf report -D' then the last module has a size that takes it to 0xFFFFFFFF which overlaps with the rest of the kernel symbols. On x86 it looks like the modules are loaded after the kernel image in VM unlike ARM. Jamie