topic warnings on AMD Athlon in Intel® Moderncode for Parallel Architectures

warnings on AMD Athlon

foobar2073 — Mon, 28 Nov 2011 05:25:47 GMT

Hi,

I report a few warnings i got while running the tbb tests on my desktop with Athlon 64 dual core (with linux 32-bits OS) cpu inside.

Should i care about them ? Is there a (simple) way to avoid them ?

./test_atomic.exe

TBB Warning: atomic store on misaligned 8-byte location 0xbfb635e4 is slow

TBB Warning: atomic store on misaligned 8-byte location 0xbfb63614 is slow

done

./test_atomic_pic.exe

TBB Warning: atomic store on misaligned 8-byte location 0xbfafa714 is slow

TBB Warning: atomic store on misaligned 8-byte location 0xbfafa754 is slow

done

[...]

./test_task_scheduler_observer.exe 1:4

done

TBB Warning: Leaked 1 observer_proxy objects

warnings on AMD Athlon

jimdempseyatthecove — Tue, 29 Nov 2011 22:23:08 GMT

Your code (or code in TBB) is performing an atomic instruction to an object of size 8-bytes to alocation that is not a multiple of 8 bytes.

A struct/class member variable is not aligned properly
And/Or an allocation is not using one of the alligned allocation routines.

See if you can determine what is located at those addresses and then determine the reason for the alignment issue.

Note, many O/S's allocation granularity is 8 or 16 bytes. Your Linux might be using 4 byte granularity. Therefore this problem might have been hidden when testing on a different system.

Jim Dempsey

warnings on AMD Athlon

TimP — Wed, 30 Nov 2011 04:06:02 GMT

Even in 32-bit linux, the software has a built-in preference for 8-byte alignments. Alignments might be reduced by use of gcc options such as those included in -Os, or by non-optimum layout (possibly with packed storage) within a struct/class.