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[Xen-devel] [PATCH] Xenoprof: Enabling performance profiling in Xen

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH] Xenoprof: Enabling performance profiling in Xen
From: William Cohen <wcohen@xxxxxxxxxx>
Date: Mon, 11 Apr 2005 16:27:27 -0400
Cc: oprofile-list <oprofile-list@xxxxxxxxxxxxxxxxxxxxx>
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I took a quick look at the patches for supporting profiling in Xen and I have some questions about the patches.

-Do all domains have to use the same setup for the performance monitoring counters? Or is there some virtualization of the performance counters?

-How is this going to interact with other performance monitoring infrastructure such as perfctr and perfmon? Or is the design going to need to be significantly revised for other performance monitoring interfaces? I like OProfile as much as anyone else, but I would like to see the Xen support allow the other interfaces to performance monitoring hardware to work.

-It appears that the multiple samples can be queued up in the hypervisor. In the OProfile kernel support when a process exits there is a flush of the per cpu buffers to make sure that the VMAs are mapped to files and offsets before the the mappings are lost. Should there be a flush of the samples from the hypervisor to make sure that they are read out before the process exits and the memory maps are lost?

-OProfile analysis tools expect the exectuable to be around when analyzing the sample files. Is the oprofile user space making the assumption that the domains have the same executables for the active and passive domains? Things could be messy if the domains are different, e.g. Fedora Core 3 domain and a Rawhide domain.

-Should get rid of xen-2.0.5/xen/arch/x86/oprofile/#Makefile# in the xen hypervisor patch.


-Will

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