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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Question: Dynamic code in x86_64 Xen
(Sorry, hit the send button too soon, in the last message) Keir, Could you please help me understand some Xen code profile that I cannot explain? When running netperf on x86_64 Xen, oprofile reports that 2% of the PC samples are not recognized (i.e. they correspond to code outside the ".text" section reported on xen image file). I added some instrumentation in oprofile and observed that these PC samples are located in: 1) for dom0: in Xen BSS section (more specifically on cpu0_stack) 2) for domU: outside any section specified in Xen image file (i.e. dynamically allocated memory) I suspect case 2 is also a stack for a different CPU which is dynamically allocated (and used in the CPU that the guest is executing) but I am not sure... Anyway, why whould Xen execute any code from the stack? Is this expected Xen behavior or this is a bug somewhere (probably in xenoprofile)? I did not see this behavior in the past when I was using x86_32 Xen. Could you please shed some light on this ... Thanks Renato >> >> -----Original Message----- >> From: Santos, Jose Renato G >> Sent: Tuesday, July 10, 2007 11:44 AM >> To: 'Keir Fraser' >> Subject: Question: Dynamic code in x86_64 Xen >> >> >> Keir, >> >> Could you please help me understand some Xen code profile >> that I cannot explain? >> When running netperf on x86_64 Xen, oprofile reports that 2% >> of the PC samples are not recognized (i.e. they correspond >> to code outside the ".text" section reported on xen image >> file). I added some instrumentation in oprofile and observed >> that these PC samples are located in: >> 1) for dom0: in Xen BSS section (more specifically on cpu0_stack) >> 2) for domU: outside any section specified in Xen image file >> (i.e. dynamically allocated memory) >> >> I suspect case 2 is also a stack for a different CPU which >> is dynamically allocated (and used in the CPU that the guest >> is executing) but I am not sure... >> >> Anyway, why whould Xen execute any code from the stack? Is >> this expected Xen behavior or this is a bug somewhere >> (probably in xenoprofile)? >> I did not see this behavior in the past when I was using x86_32 Xen. >> Could you please >> >> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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