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S_Goswami
Beginner
42 Views

Only lightweight-hotspots works without crashing

Hi, I am running into the following problem. The hardware EBS based analysis (lightweight-hotpspots) appears to work, but any other analysis has to be stooped manually or else crashes the system. I am running the latest Vtune for Linux on a "Intel Xeon CPU X5680 @3.33GHz" platform. The soruce is compiled with "gcc -O3 -g" .

does not work:
===========
amplxe-cl -verbose -collect locksandwaits -duration 30 -target-pid 5541

Ends with the following

Error: Error 0x4000001d (Cannot find raw collector data) -- Cannot re-finalize the result: it has no raw collector data.



does work:
===========
amplxe-cl -verbose -collect lightweight-hotspots -duration 30 -target-pid 5541




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5 Replies
Peter_W_Intel
Employee
42 Views

I saw similar reports from others. I guess that isan application specific issue - it means, if the user ran user-mode sampling data collection (hotspots, concurrency, locksandwaits)to attach a running process, which is a service application, the collector will crash that target application...

Because user-mode sampling will doinstrumentation of the target process dynamically- and your service application may work on system mode, which will cause unexpected results.

But for hardware event-based, data collector works in system mode, should have no this issue; User-mode sampling with attach-to-process should work with general applications - they are user mode applications.

Regards, Peter
S_Goswami
Beginner
42 Views

Thanks Peter. It will be very userful to understand what excatly in a daemon code makes dynamic instrumentation not compatible with user mode sampling. Can you please shed some on that ?
Peter_W_Intel
Employee
42 Views

In simple words, user-mode sampling is not suitableto workwith device driver, system module (Linux or Windows kernel module), service applications.

The reason is that daemon code possibly be usedby many processes -it doesn't make sense to instrument them at runtime.

Thanks, Peter
42 Views

I ran into that same error message too for user-mode sampling analysis (hw event-based ones worked). In my case the issue was due to running the target application under a regular user and amplxe-cl under root; once I executed both the app and amplxe-cl under the regular user the user-mode sampling analysisworked without problems.

Best,
-Rilson
Peter_W_Intel
Employee
42 Views

I ran into that same error message too for user-mode sampling analysis (hw event-based ones worked). In my case the issue was due to running the target application under a regular user and amplxe-cl under root; once I executed both the app and amplxe-cl under the regular user the user-mode sampling analysisworked without problems.

Best,
-Rilson

You solved a "privilege" issue if you used "root" user, amplxe-cl will tryto instrument running process in ring0.If log on a regular user, amplxe-cl cannot instrument the process in ring0, only caninstrument ring3 application- However ifring0 processis shared (used) bymultiple applications, it will cause unexpectedresult, e.g. abnormally exit.

Regards, Peter

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