Thank you, Tom. I'll try that after I'm off of work tonight. And thank you for the great ideas, Nathan. On Fri, Feb 21, 2014 at 2:39 AM, West, Nathan <n...@ostatemail.okstate.edu> wrote: > On Thu, Feb 20, 2014 at 11:25 PM, Kelly Boswell <krbosw...@gmail.com> wrote: >> After the make test failed for this module, I decided to poke around to see >> if there is an easy fix. I made a script that simply executes the test over >> and over until it seg faults and exits after the core file is created. >> >> xxxxx@xxxx:~/src/gnuradio/build/gr-digital/python/digital$ ./runtests.sh >> Using Volk machine: avx_64_mmx >> Segmentation fault (core dumped) >> >> xxxxx@xxxx:~/src/gnuradio/build/gr-digital/python/digital$ gdb >> /usr/bin/python2.7 core >> (gdb) bt >> (gdb) bt >> #0 0x00007fe8f627fb17 in volk_32fc_32f_dot_prod_32fc_a_avx () >> from /home/kelly/src/gnuradio/build/volk/lib/libvolk.so.0.0.0 >> #1 0x00007fe8f52dd25f in >> gr::filter::kernel::fir_filter_ccf::filter(std::complex<float> const*) () >> from >> /home/kelly/src/gnuradio/build/gr-filter/lib/libgnuradio-filter-3.8git.so.0.0.0 >> #2 0x00007fe8f143c45b in >> gr::digital::pfb_clock_sync_ccf_impl::general_work(int, std::vector<int, >> std::allocator<int> >&, std::vector<void const*, std::allocator<void const*> >>>&, std::vector<void*, std::allocator<void*> >&) () >> from >> /home/kelly/src/gnuradio/build/gr-digital/lib/libgnuradio-digital-3.8git.so.0.0.0 >> #3 0x00007fe8f653809e in gr::block_executor::run_one_iteration() () >> from >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0 >> #4 0x00007fe8f6573622 in >> gr::tpb_thread_body::tpb_thread_body(boost::shared_ptr<gr::block>, int) () >> from >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0 >> #5 0x00007fe8f6565ea1 in >> boost::detail::function::void_function_obj_invoker0<gr::thread::thread_body_wrapper<gr::tpb_container>, >> void>::invoke(boost::detail::function::function_buffer&) () >> from >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0 >> ---Type <return> to continue, or q <return> to quit--- >> #6 0x00007fe8f6526610 in boost::detail::thread_data<boost::function0<void> >>>::run() () >> from >> /home/kelly/src/gnuradio/build/gnuradio-runtime/lib/libgnuradio-runtime-3.8git.so.0.0.0 >> #7 0x00007fe8f9adc94a in ?? () >> from /usr/lib/x86_64-linux-gnu/libboost_thread.so.1.53.0 >> #8 0x00007fe8fc8a3f6e in start_thread (arg=0x7fe8e2ffd700) >> at pthread_create.c:311 >> #9 0x00007fe8fc5ce9cd in clone () >> at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113 >> >> Of course, I had to recompile it with debugging info to glean anything >> useful from the stack trace. So, I did that and I traced the bug to this >> line: >> >> c0Val = _mm256_mul_ps(a0Val, b0Val); >> >> I can't dump the values in a0Val or b0Val, though, because they're >> intermediate values that are optimized away by the optimized kernel code. I >> tried stepping through the assembler instructions but I'm not familiar with >> the various sse and avx extensions. Heck, I'm not even familiar with the >> x86_64 instruction set. So I have a huge learning curve ahead of me, there. >> Is it possible to just dump the values in these __m256 data types to a file >> so I can debug it that way? If that's not easy to do, then I'm willing to >> learn what I have to about the instruction set so I can debug this thing. >> But I would sure appreciate some help if anyone has some advice to offer. >> >> Software version: >> I rebased to the latest version of the next branch last night before I went >> to bed at around 1:30 am CDT. >> >> Operating System: >> kelly@octs2:~/src/gnuradio/volk/kernels/volk$ uname -a >> Linux octs2 3.11.0-17-generic #31-Ubuntu SMP Mon Feb 3 21:52:43 UTC 2014 >> x86_64 x86_64 x86_64 GNU/Linux >> It's Ubuntu 13.10 >> >> Hardware: ASUS X750J >> Intel Quad Core i7 4700HQ 2.4GHz >> >> cpuinfo: >> processor : 7 >> vendor_id : GenuineIntel >> cpu family : 6 >> model : 60 >> model name : Intel(R) Core(TM) i7-4700HQ CPU @ 2.40GHz >> stepping : 3 >> microcode : 0x8 >> cpu MHz : 2401.000 >> cache size : 6144 KB >> physical id : 0 >> siblings : 8 >> core id : 3 >> cpu cores : 4 >> apicid : 7 >> initial apicid : 7 >> fpu : yes >> fpu_exception : yes >> cpuid level : 13 >> wp : yes >> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov >> pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb >> rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology >> nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est >> tm2 ssse3 fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt >> tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat epb >> xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase >> tsc_adjust bmi1 avx2 smep bmi2 erms invpcid >> bogomips : 4789.27 >> clflush size : 64 >> cache_alignment : 64 >> address sizes : 39 bits physical, 48 bits virtual >> power management: >> > > > Hi Kelly, > > First, this is great debugging, thanks for getting so much info and > trying to go for a fix on your own. > > On to the good stuff. I was able to reproduce this on my i7-4700MQ. > Here's some additional info for the logs: > > * constellation_receiver is a hier block with a fir_filter_ccf inside > that is calling the volk avx dot product. > * The avx dot product proto-kernel passes VOLK QA > * The qa_fir_filter.py is testing a fir_filter_ccf that passes its QA. > * Just for kicks, I forced VOLK to use the generic kernel and I still > see the segfault. > > A couple of things I'd like to try (and please feel free to give these a try): > * Go back to a commit just before fir_filter.cc started using > volk_malloc and volk_free. (or for bonus points go back to some point > in time when this test always passes and do a git bisect) > * fiddle with parameters of the test, data length, number of taps in > filter, etc. > * Doubtful this would change, but test on different processors. It > would be pretty wild if there was something off in the 4700 line, but > the fact that the generic proto-kernel had the same result and nobody > else has reported this yet is suspicious. My guess is GCC is actually > emitting *very* similar code for the generic and avx dot product > proto-kernels. > > Nathan
I was having similar issues this week with some AVX boxes. It looks like it's a problem using posix_memalign (which is called by volk_malloc if posix_memalign is available). Removing the use of posix_memalign solves my problem. I'll work with Nathan off-list to see about fixing this, possibly by removing the use of that version of malloc. Tom
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