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printf("") giving segmentation fault

Hi AMD,

My system specification is: Intel i3 sandybridge CPU, HD 7970 GPU, Ubuntu 12.04 OS

Device OpenCL C version:                       OpenCL C 1.2

  Driver version:                                CAL 1.4.1720 (VM)

  Profile:                                       FULL_PROFILE

  Version:                                       OpenCL 1.2 AMD-APP (923.1)

It may not be a serious issue, but it certainly is annoying.

Here is the backtrace when i ran it on CPU:

Program received signal SIGSEGV, Segmentation fault.

0x00007ffff613809b in llvm::ConstantArray::isString() const () from /usr/lib/libamdocl64.so

(gdb) bt

#0  0x00007ffff613809b in llvm::ConstantArray::isString() const () from /usr/lib/libamdocl64.so

#1  0x00007ffff59ad1e6 in (anonymous namespace)::AMDILPrintfConvert::expandPrintf(llvm::ilist_iterator<llvm::Instruction>*) ()

   from /usr/lib/libamdocl64.so

#2  0x00007ffff59acd24 in (anonymous namespace)::AMDILPrintfConvert::runOnFunction(llvm::Function&) () from /usr/lib/libamdocl64.so

#3  0x00007ffff61dc630 in llvm::FPPassManager::runOnFunction(llvm::Function&) () from /usr/lib/libamdocl64.so

#4  0x00007ffff61dc742 in llvm::FunctionPassManagerImpl::run(llvm::Function&) () from /usr/lib/libamdocl64.so

#5  0x00007ffff61dc8d9 in llvm::FunctionPassManager::run(llvm::Function&) () from /usr/lib/libamdocl64.so

#6  0x00007ffff5482812 in amd::CompilerImpl::llvmCodeGen(llvm::Module*, std::string&, amd::CompilerTargetInfo&, llvm::JunkJITBinary**) () from /usr/lib/libamdocl64.so

#7  0x00007ffff5486e18 in amd::CompilerImpl::llvmLinkOptCG(std::string&, std::string&, amd::CompilerTargetInfo&, llvm::JunkJITBinary**) () from /usr/lib/libamdocl64.so

#8  0x00007ffff54c3f37 in gpu::NullProgram::compileBinaryToIL(amd::option::Options*) () from /usr/lib/libamdocl64.so

#9  0x00007ffff54e769c in gpu::NullProgram::linkImpl(amd::option::Options*) () from /usr/lib/libamdocl64.so

#10 0x00007ffff548ed3e in device::Program::build(std::string const&, char const*, amd::option::Options*) ()

   from /usr/lib/libamdocl64.so

#11 0x00007ffff549c338 in amd::Program::build(std::vector<amd::Device*, std::allocator<amd::Device*> > const&, char const*, void (*)(_cl_program*, void*), void*, bool) () from /usr/lib/libamdocl64.so

#12 0x00007ffff547d5e7 in clBuildProgram () from /usr/lib/libamdocl64.so

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1 Solution

The hardware has 64KB, but the largest allocation is 32KB, hence the limit.

View solution in original post

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6 Replies

another small bug is in clinfo output. Local Memory Size on tahiti is 64KB( it reports 32KB), GPU Max Clock is 925MHz( it reports 0MHZ).

clinfo:

Number of platforms:                             2
  Platform Profile:                              FULL_PROFILE
  Platform Version:                              OpenCL 1.2 AMD-APP (923.1)
  Platform Name:                                 AMD Accelerated Parallel Processing
  Platform Vendor:                               Advanced Micro Devices, Inc.
  Platform Extensions:                           cl_khr_icd cl_amd_event_callback cl_amd_offline_devices
  Platform Profile:                              FULL_PROFILE
  Platform Version:                              OpenCL 1.1 LINUX
  Platform Name:                                 Intel(R) OpenCL
  Platform Vendor:                               Intel(R) Corporation
  Platform Extensions:                           cl_khr_fp64 cl_khr_icd cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_intel_printf cl_ext_device_fission cl_intel_exec_by_local_thread


  Platform Name:                                 AMD Accelerated Parallel Processing
Number of devices:                               2
  Device Type:                                   CL_DEVICE_TYPE_GPU
  Device ID:                                     4098
  Board name:                                    AMD Radeon HD 7900 Series
  Device Topology:                               PCI[ B#1, D#0, F#0 ]
  Max compute units:                             32
  Max work items dimensions:                     3
    Max work items[0]:                           256
    Max work items[1]:                           256
    Max work items[2]:                           256
  Max work group size:                           256
  Preferred vector width char:                   16
  Preferred vector width short:                  8
  Preferred vector width int:                    4
  Preferred vector width long:                   2
  Preferred vector width float:                  4
  Preferred vector width double:                 2
  Native vector width char:                      16
  Native vector width short:                     8
  Native vector width int:                       4
  Native vector width long:                      2
  Native vector width float:                     4
  Native vector width double:                    2
  Max clock frequency:                           0Mhz
  Address bits:                                  32
  Max memory allocation:                         536870912
  Image support:                                 Yes
  Max number of images read arguments:           128
  Max number of images write arguments:          8
  Max image 2D width:                            8192
  Max image 2D height:                           8192
  Max image 3D width:                            2048
  Max image 3D height:                           2048
  Max image 3D depth:                            2048
  Max samplers within kernel:                    16
  Max size of kernel argument:                   1024
  Alignment (bits) of base address:              2048
  Minimum alignment (bytes) for any datatype:    128
  Single precision floating point capability
    Denorms:                                     No
    Quiet NaNs:                                  Yes
    Round to nearest even:                       Yes
    Round to zero:                               Yes
    Round to +ve and infinity:                   Yes
    IEEE754-2008 fused multiply-add:             Yes
  Cache type:                                    Read/Write
  Cache line size:                               64
  Cache size:                                    16384
  Global memory size:                            2147483648
  Constant buffer size:                          65536
  Max number of constant args:                   8
  Local memory type:                             Scratchpad
  Local memory size:                             32768
  Kernel Preferred work group size multiple:     64
  Error correction support:                      0
  Unified memory for Host and Device:            0
  Profiling timer resolution:                    1
  Device endianess:                              Little
  Available:                                     Yes
  Compiler available:                            Yes
  Execution capabilities:
    Execute OpenCL kernels:                      Yes
    Execute native function:                     No
  Queue properties:
    Out-of-Order:                                No
    Profiling :                                  Yes
  Platform ID:                                   0x7f658d6880a0
  Name:                                          Tahiti
  Vendor:                                        Advanced Micro Devices, Inc.
  Device OpenCL C version:                       OpenCL C 1.2
  Driver version:                                CAL 1.4.1720 (VM)
  Profile:                                       FULL_PROFILE
  Version:                                       OpenCL 1.2 AMD-APP (923.1)
  Extensions:                                    cl_khr_fp64 cl_amd_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_3d_image_writes cl_khr_byte_addressable_store cl_khr_gl_sharing cl_ext_atomic_counters_32 cl_amd_device_attribute_query cl_amd_vec3 cl_amd_printf cl_amd_media_ops cl_amd_popcnt


  Device Type:                                   CL_DEVICE_TYPE_CPU
  Device ID:                                     4098
  Board name:
  Max compute units:                             4
  Max work items dimensions:                     3
    Max work items[0]:                           1024
    Max work items[1]:                           1024
    Max work items[2]:                           1024
  Max work group size:                           1024
  Preferred vector width char:                   16
  Preferred vector width short:                  8
  Preferred vector width int:                    4
  Preferred vector width long:                   2
  Preferred vector width float:                  4
  Preferred vector width double:                 0
  Native vector width char:                      16
  Native vector width short:                     8
  Native vector width int:                       4
  Native vector width long:                      2
  Native vector width float:                     4
  Native vector width double:                    0
  Max clock frequency:                           3300Mhz
  Address bits:                                  64
  Max memory allocation:                         2147483648
  Image support:                                 Yes
  Max number of images read arguments:           128
  Max number of images write arguments:          8
  Max image 2D width:                            8192
  Max image 2D height:                           8192
  Max image 3D width:                            2048
  Max image 3D height:                           2048
  Max image 3D depth:                            2048
  Max samplers within kernel:                    16
  Max size of kernel argument:                   4096
  Alignment (bits) of base address:              1024
  Minimum alignment (bytes) for any datatype:    128
  Single precision floating point capability
    Denorms:                                     Yes
    Quiet NaNs:                                  Yes
    Round to nearest even:                       Yes
    Round to zero:                               Yes
    Round to +ve and infinity:                   Yes
    IEEE754-2008 fused multiply-add:             Yes
  Cache type:                                    Read/Write
  Cache line size:                               64
  Cache size:                                    32768
  Global memory size:                            4138541056
  Constant buffer size:                          65536
  Max number of constant args:                   8
  Local memory type:                             Global
  Local memory size:                             32768
  Kernel Preferred work group size multiple:     1
  Error correction support:                      0
  Unified memory for Host and Device:            1
  Profiling timer resolution:                    1
  Device endianess:                              Little
  Available:                                     Yes
  Compiler available:                            Yes
  Execution capabilities:
    Execute OpenCL kernels:                      Yes
    Execute native function:                     Yes
  Queue properties:
    Out-of-Order:                                No
    Profiling :                                  Yes
  Platform ID:                                   0x7f658d6880a0
  Name:                                          Intel(R) Core(TM) i3-2120 CPU @ 3.30GHz
  Vendor:                                        GenuineIntel
  Device OpenCL C version:                       OpenCL C 1.2
  Driver version:                                2.0 (sse2,avx)
  Profile:                                       FULL_PROFILE
  Version:                                       OpenCL 1.2 AMD-APP (923.1)
  Extensions:                                    cl_khr_fp64 cl_amd_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_byte_addressable_store cl_khr_gl_sharing cl_ext_device_fission cl_amd_device_attribute_query cl_amd_vec3 cl_amd_printf cl_amd_media_ops cl_amd_popcnt


  Platform Name:                                 Intel(R) OpenCL
Number of devices:                               1
  Device Type:                                   CL_DEVICE_TYPE_CPU
  Device ID:                                     32902
  Max compute units:                             4
  Max work items dimensions:                     3
    Max work items[0]:                           1024
    Max work items[1]:                           1024
    Max work items[2]:                           1024
  Max work group size:                           1024
  Preferred vector width char:                   16
  Preferred vector width short:                  8
  Preferred vector width int:                    4
  Preferred vector width long:                   2
  Preferred vector width float:                  4
  Preferred vector width double:                 2
  Native vector width char:                      16
  Native vector width short:                     8
  Native vector width int:                       4
  Native vector width long:                      2
  Native vector width float:                     4
  Native vector width double:                    2
  Max clock frequency:                           3300Mhz
  Address bits:                                  64
  Max memory allocation:                         1034635264
  Image support:                                 Yes
  Max number of images read arguments:           480
  Max number of images write arguments:          480
  Max image 2D width:                            8192
  Max image 2D height:                           8192
  Max image 3D width:                            2048
  Max image 3D height:                           2048
  Max image 3D depth:                            2048
  Max samplers within kernel:                    480
  Max size of kernel argument:                   3840
  Alignment (bits) of base address:              1024
  Minimum alignment (bytes) for any datatype:    128
  Single precision floating point capability
    Denorms:                                     Yes
    Quiet NaNs:                                  Yes
    Round to nearest even:                       Yes
    Round to zero:                               No
    Round to +ve and infinity:                   No
    IEEE754-2008 fused multiply-add:             No
  Cache type:                                    Read/Write
  Cache line size:                               64
  Cache size:                                    262144
  Global memory size:                            4138541056
  Constant buffer size:                          131072
  Max number of constant args:                   480
  Local memory type:                             Global
  Local memory size:                             32768
  Kernel Preferred work group size multiple:     128
  Error correction support:                      0
  Unified memory for Host and Device:            1
  Profiling timer resolution:                    1
  Device endianess:                              Little
  Available:                                     Yes
  Compiler available:                            Yes
  Execution capabilities:
    Execute OpenCL kernels:                      Yes
    Execute native function:                     Yes
  Queue properties:
    Out-of-Order:                                Yes
    Profiling :                                  Yes
  Platform ID:                                   0x1974468
  Name:                                                  Intel(R) Core(TM) i3-2120 CPU @ 3.30GHz
  Vendor:                                        Intel(R) Corporation
  Device OpenCL C version:                       OpenCL C 1.1
  Driver version:                                1.1
  Profile:                                       FULL_PROFILE
  Version:                                       OpenCL 1.1 (Build 31360.31426)
  Extensions:                                    cl_khr_fp64 cl_khr_icd cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_intel_printf cl_ext_device_fission cl_intel_exec_by_local_thread

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IIRC one work group can access only half of LDS on Tahity.

Hi nou,

Is that so?

It would make sense to use even less LDS, so that apt number of WGs(IMHO atleast 8 wavefronts) can run on a compute Unit.

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The hardware has 64KB, but the largest allocation is 32KB, hence the limit.

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Please supply a test case that shows the failure so we can debug this.

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Hi Micah,

I think the test case is easy to construct. I just modified bitonic sort kernel as follows and the sample crashed for me on my windows machine also.

#pragma OPENCL EXTENSION cl_amd_printf:enable

__kernel

void bitonicSort(__global uint * theArray,

                 const uint stage,

                 const uint passOfStage,

                 const uint width,

                 const uint direction)

{

    uint sortIncreasing = direction;

    uint threadId = get_global_id(0);

    uint pairDistance = 1 << (stage - passOfStage);

    uint blockWidth   = 2 * pairDistance;

          printf("");

    uint leftId = (threadId % pairDistance)

                   + (threadId / pairDistance) * blockWidth;

........

and thanks for clarifying about LOCAL Mem Size