From: B. N. P. <poo...@in...> - 2007-04-03 13:23:10
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Hello, We are noticing some problem with the opcontrol utility of oprofile in the version 0.8.1 (and even the latest cvs code). If we pass the kernel range vma address to opcontrol using the --kernel-range option, the profiling data that we get do not correspond to the kernel-range addresses passed. For example, opcontrol --start --kernel-range=43334f84,432a4c90 will give us the output: ******************************************************************************************** vma samples % image name app name symbol name 000849d0 1 0.0851 vmlinux cat pipe_writev 000202e6 1 0.0851 vmlinux sshd sysc_do_restart 0000089a 1 0.0851 vmlinux vmlinux .lowcase 00031d34 1 0.0851 vmlinux vmlinux __do_softirq 0006a03c 1 0.0851 vmlinux vmlinux anon_vma_prepare 00062c84 1 0.0851 vmlinux vmlinux clear_page_tables 00064330 1 0.0851 vmlinux vmlinux do_wp_page 00199a00 1 0.0851 vmlinux vmlinux ip_rcv *********************************************************************************************** This does not seem to change for different values of --kernel-range passed. Maynard P. Johnson (cced in the mail)/ /has tried to use the latest cvs version, but still could not get this work. Can someone throw more light on if this is the right way to use the option, is this a bug and if so, has it been fixed in any of the recent releases? Regards, Poornima |
From: Maynard J. <may...@us...> - 2007-04-11 14:16:53
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B. N. Poornima wrote: > Hello, > We are noticing some problem with the opcontrol utility of oprofile in > the version 0.8.1 (and even the latest cvs code). > If we pass the kernel range vma address to opcontrol using the > --kernel-range option, the profiling data that we get do not correspond > to the kernel-range addresses passed. I've been looking into this some more and trying to understand the intended use of the --kernel-range option. Firstly, it seems that in your example, you have the start and end addresses swapped. Maybe that's not the way you actually specified it when you ran oprofile, since I believe your output would have shown no vmlinux samples at all if your start value was greater than end value. After looking at the code, it appears to me that the --kernel-range option is NOT intended as a filtering mechanism for recording samples that fall within the specified range -- but that seems to be your intended use. Instead, I believe it is meant for the user to specify the actual VMA range in memory where the kernel resides. For pLinux, this isn't necessary since the kernel is loaded into memory at the starting address specified as the starting VMA in the vmlinux image. Maybe --kernel-range is required for other flavors of Linux. Does anyone on the list know the history of this option -- i.e., why does it exist? Regards, -Maynard > For example, > > opcontrol --start --kernel-range=43334f84,432a4c90 will give us the output: > ******************************************************************************************** > vma samples % image name app name symbol name > 000849d0 1 0.0851 vmlinux cat pipe_writev > 000202e6 1 0.0851 vmlinux sshd sysc_do_restart > 0000089a 1 0.0851 vmlinux vmlinux .lowcase > 00031d34 1 0.0851 vmlinux vmlinux __do_softirq > 0006a03c 1 0.0851 vmlinux vmlinux anon_vma_prepare > 00062c84 1 0.0851 vmlinux vmlinux clear_page_tables > 00064330 1 0.0851 vmlinux vmlinux do_wp_page > 00199a00 1 0.0851 vmlinux vmlinux ip_rcv > *********************************************************************************************** > > This does not seem to change for different values of --kernel-range > passed. Maynard P. Johnson (cced in the mail)/ /has tried to use the > latest cvs version, but still could not get this work. Can someone throw > more light on if this is the right way to use the option, is this a bug > and if so, has it been fixed in any of the > recent releases? > > Regards, > Poornima > > > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys-and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > oprofile-list mailing list > opr...@li... > https://lists.sourceforge.net/lists/listinfo/oprofile-list |
From: John L. <le...@mo...> - 2007-04-11 14:59:04
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On Wed, Apr 11, 2007 at 09:16:41AM -0500, Maynard Johnson wrote: > Does anyone on the list know the history of this option -- i.e., why > does it exist? We've historically had problems on some platforms with getting the start/end range of the kernel text correct. This was useful as a workaround only. They are indeed misusing it, it should never be specified barring bugs. john |