diff options
| -rw-r--r-- | intern/cycles/kernel/kernel_compat_cpu.h | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/intern/cycles/kernel/kernel_compat_cpu.h b/intern/cycles/kernel/kernel_compat_cpu.h index 37cba03ff97..08c8bdd369d 100644 --- a/intern/cycles/kernel/kernel_compat_cpu.h +++ b/intern/cycles/kernel/kernel_compat_cpu.h @@ -25,10 +25,12 @@ #include "util_half.h" #include "util_types.h" -/* On 64bit linux single precision exponent is really slow comparing to the - * double precision version, even with float<->double conversion involved. +/* On x86_64, versions of glibc < 2.16 have an issue where expf is + * much slower than the double version. This was fixed in glibc 2.16. */ -#if !defined(__KERNEL_GPU__) && defined(__linux__) && defined(__x86_64__) +#if !defined(__KERNEL_GPU__) && defined(__x86_64__) && defined(__x86_64__) && \ + defined(__GNU_LIBRARY__) && defined(__GLIBC__ ) && defined(__GLIBC_MINOR__) && \ + (__GLIBC__ <= 2 && __GLIBC_MINOR__ < 16) # define expf(x) ((float)exp((double)(x))) #endif |