From: Robert R. <rob...@am...> - 2010-09-23 15:13:22
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On 23.09.10 10:02:30, Maynard Johnson wrote: > On 09/23/2010 5:50 AM, C K Kashyap wrote: > > Hi, > > I was wondering if I've missed any setting/flag to get the kernel > > callgraph correctly? > > > > On Fri, Sep 17, 2010 at 12:05 PM, C K Kashyap<ckk...@gm...> wrote: > >>> What oprofile version are you using and what's your architecture and > >>> processor type? Callgraph is not supported on all architectures. Some > >>> examples where it *is* supported are: x86, ppc64, and ARM. > >>> > >> My kernel/OS details as follows - > >> Linux mymachine 2.6.18-128.el5 #1 SMP Wed Dec 17 11:41:38 EST 2008 This kernel is not very up-to-date, support for model 23 has been added to v2.6.27. Does this kernel include backports or are you running in timer mode? > >> x86_64 x86_64 x86_64 GNU/Linux > >> > >> Oprofile version - opcontrol: oprofile 0.9.3 compiled on Sep 3 2008 00:41:52 > >> > >> Some data about the hardware - > >> vendor_id : GenuineIntel > >> cpu family : 6 > >> model : 23 > >> model name : Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz > >> > >> > >> So, I am able to generate callgraph for user apps. Its the kernel > >> where I dont see goot result. > > Yes, sorry, that slipped by me -- the snippet of opreport you pasted into your > note seemed to imply that neither userspace nor kernelspace callgraph'ing was > working. Please provide the final stats reported in the oprofiled.log. That > will help us determine if this is an oprofile userspace issue or an oprofile > kernel driver issue. It may not be definitive . . . we may have to dig deeper > by collecting verbose output. But running with --verbose even without callgraph > enabled can severely impact results due to the high overhead. Then when you add > the high overhead of callgraph, verbose enablement can result in so many lost > samples that it's almost useless without careful tweaking of buffer sizes and > sampling frequencies. Before we dig deeper here we should test the latest or some stable kernel. I don't much trust this v2.6.18 version and its potential backports. > > *Robert*, have you heard of anything like this before? I didn't touch the callgraph code so far nor I am aware of a regression or bug reports. Though I don't know if it really works since I am not using it. -Robert -- Advanced Micro Devices, Inc. Operating System Research Center |