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Workaround for -m 22100 on NVIDIA

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This commit is contained in:
Jens Steube 2020-03-18 16:13:57 +01:00
parent a6cf7caf4a
commit 24094793da
1 changed files with 27 additions and 3 deletions
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30
OpenCL/m22100-pure.cl
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@ -265,11 +265,35 @@ KERNEL_FQ void m22100_loop (KERN_ATTR_TMPS_ESALT (bitlocker_tmp_t, bitlocker_t))
{
#ifdef REAL_SHM
for (u32 i = lid; i < FIXED_ITER_INCR; i += lsz)
/**
* On NVIDIA, the __sync_threads() is not working as expected if called from inside a loop.
* This is a unique situation across all hashcat kernels so far.
* From CUDA manual:
* __syncthreads() is allowed in conditional code but only if the conditional evaluates identically across the entire thread block,
* otherwise the code execution is likely to hang or produce unintended side effects.
* NVIDIA OpenCL runtime is also affected, but other OpenCL runtimes work as they should.
* An workaround exists by disabling shared memory access. Speed drop is around 4%.
* Another workaround is to let only a single thread do all the work while all other threads wait for it to finish. Speed drop is around 0.05%.
// original code
for (int i = lid; i < FIXED_ITER_INCR; i += lsz)
{
for (int j = 0; j < 48; j++) // first 16 set to register
{
s_wb_ke_pc[i][j] = esalt_bufs[digests_offset].wb_ke_pc[loop_pos + t + i][j];
}
}
*/
if (lid == 0)
{
for (u32 j = 0; j < 48; j++) // first 16 set to register
for (int i = 0; i < FIXED_ITER_INCR; i++)
{
s_wb_ke_pc[i][j] = esalt_bufs[digests_offset].wb_ke_pc[loop_pos + t + i][j];
for (int j = 0; j < 48; j++) // first 16 set to register
{
s_wb_ke_pc[i][j] = esalt_bufs[digests_offset].wb_ke_pc[loop_pos + t + i][j];
}
}
}