Messages in this thread | | | Date | Fri, 29 Apr 2011 11:04:46 -0400 (EDT) | From | Vince Weaver <> | Subject | re-enable Nehalem raw Offcore-Events support |
| |
Hello Linus
can you revert the commit b52c55c6a25e4515b5e075a989ff346fc251ed09
This removed functionality from perf_events that allowed raw event access for OFFCORE_EVENTS type events on Nehalem and Westmere cpus.
To be fair, this is not technically a regression as the feature was only (finally!) added in the 2.6.39 merge window. However this is a useful feature and many tools (including the PAPI performance counter library that I work on) had added support for it in anticipation of the 2.6.39 release.
Ingo's reasons for removing the feature seem to boil down to 1. "perf" doesn't use the functionality, and any other userspace program that uses the perf_events syscalls don't matter 2. Users are too stupid to use the raw functionality properly; we should only allow a kernel-developer-approved small subset of the features provided by the CPU as described in the intel developers manuals.
#2 seems like a gross misinterpretation of the whole "Linux gives you enough rope to shoot yourself in the foot" policy from days passed, but maybe things have moved on.
Thanks,
Vince vweaver1@eecs.utk.edu
| |