Bug: cpu_set_t is undefined in specific Android Archs, making compilation impossible

[Vali-98]

What happened?

Changes to thread affinity cause Android builds to use:

static bool lm_ggml_thread_apply_affinity(const bool * mask) {
    cpu_set_t cpuset;
    int err;

    CPU_ZERO(&cpuset);

    for (uint32_t i = 0; i < LM_GGML_MAX_N_THREADS; i++) {
        if (mask[i]) {
            LM_GGML_PRINT_DEBUG("Thread %lx: adding %d to cpuset\n", pthread_self(), i);
            CPU_SET(i, &cpuset);
        }
    }
    ...

However, cpu_set_t, CPU_SET and CPU_ZERO does not necessarily exist in all Android NDK versions, causing specific pipelines to fail.

A simple fix would be to add the following definitions:

#ifdef __ANDROID__
#define CPU_SETSIZE 1024
#define __NCPUBITS  (8 * sizeof (unsigned long))
typedef struct
{
   unsigned long __bits[CPU_SETSIZE / __NCPUBITS];
} cpu_set_t;

#define CPU_SET(cpu, cpusetp) \
  ((cpusetp)->__bits[(cpu)/__NCPUBITS] |= (1UL << ((cpu) % __NCPUBITS)))
#define CPU_ZERO(cpusetp) \
  memset((cpusetp), 0, sizeof(cpu_set_t))
#endif

However, this solution seems ineligant. I'm not an in-depth android developer so I'm not sure if there is a more poignant solution.

Name and Version

Custom pipeline for android arm64-v8a

What operating system are you seeing the problem on?

Windows

Relevant log output

No response

[ngxson]

After #9336, the code branch using cpu_set_t will not longer built on android. So I assume that you won't get this error anymore.

[Vali-98]

Tested in my pipeline and working. Issue resolved. 👍