> Is there some reason not to enable frame pointers? It makes code slower.
Especially on Atom CPUs, where it causes pipeline stalls, but also to some degree on others, because you lose one register and spend a little bit of time setting it up, so making small functions more expensive. Another issue is that you can't enable it on a lot of existing libraries, sometimes not even with a recompile. For example glibc assembler functions do not support it at all, which is a very common case. They are designed to use dwarf, but in practice dwarf is very slow (perf has to save the stack for every sample) and in practice doesn't always work (too small stack saving, wrong annotations, out of date or broken dwarf library etc.) LBR callstack mode is not perfect either, and it has its own tradeoffs, but in many cases it seems to be a good and more efficient replacement for dwarf, when FP is not available. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
