open-gpu-kernel-modules/kernel-open/nvidia-uvm/uvm_thread_context_test.c

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    Copyright (c) 2015-2019 NVIDIA Corporation

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#include "uvm_api.h"
#include "uvm_thread_context.h"
#include "uvm_va_space.h"
#include "uvm_kvmalloc.h"
#include "uvm_test.h"


static NvU64 timed_udelay(NvU64 delay_us)
{
    NvU64 start = NV_GETTIME();

    udelay(delay_us);

    return NV_GETTIME() - start;
}

static NvU64 timed_udelay_entry(NvU64 delay_us)
{
    UVM_ENTRY_RET(timed_udelay(delay_us));
}

// Measure the overhead of wrapping entry functions i.e. the overhead of
// adding and removing a thread context.
NV_STATUS uvm_test_thread_context_perf(UVM_TEST_THREAD_CONTEXT_PERF_PARAMS *params, struct file *filp)
{
    NvU64 start;
    NvU32 i;
    uvm_thread_context_t *thread_context;
    uvm_thread_context_wrapper_t thread_context_wrapper_backup;
    const NvU64 delay_us = params->delay_us;
    NvU64 total_delay_ns = 0;

    if (params->iterations == 0)
        return NV_ERR_INVALID_ARGUMENT;

    TEST_CHECK_RET(uvm_thread_context_present());
    TEST_CHECK_RET(uvm_thread_context_wrapper_is_used());

    thread_context = uvm_thread_context();
    uvm_thread_context_save(&thread_context_wrapper_backup.context);

    // Remove the current thread context, forcing UVM_ENTRY_VOID to register a
    // new thread context instead of reusing the existing one.
    uvm_thread_context_remove(thread_context);
    TEST_CHECK_RET(!uvm_thread_context_present());

    start = NV_GETTIME();

    for (i = 0; i < params->iterations; i++) {
        if (delay_us > 0)
            total_delay_ns += timed_udelay_entry(delay_us);
        else
            UVM_ENTRY_VOID();
    }

    // Report average iteration time
    params->ns = ((NV_GETTIME() - start - total_delay_ns) / params->iterations);

    TEST_CHECK_RET(uvm_thread_context_add(thread_context));
    TEST_CHECK_RET(uvm_thread_context_present());

    uvm_thread_context_restore(&thread_context_wrapper_backup.context);

    return NV_OK;
}

static uvm_thread_context_t *inner_thread_context(void)
{
    UVM_ENTRY_RET(uvm_thread_context());
}

NV_STATUS uvm_test_thread_context_sanity(UVM_TEST_THREAD_CONTEXT_SANITY_PARAMS *params, struct file *filp)
{
    NvU32 i;
    uvm_thread_context_t *thread_context, *nested_thread_context;
    uvm_thread_context_wrapper_t thread_context_wrapper_backup;

    if (params->iterations == 0)
        return NV_ERR_INVALID_ARGUMENT;

    TEST_CHECK_RET(uvm_thread_context_present());
    TEST_CHECK_RET(uvm_thread_context_wrapper_is_used());

    thread_context = uvm_thread_context();

    // Nested entry points do not add new thread contexts. Instead, they reuse
    // the top-most thread context.
    nested_thread_context = inner_thread_context();
    TEST_CHECK_RET(nested_thread_context == thread_context);

    uvm_thread_context_save(&thread_context_wrapper_backup.context);

    uvm_thread_context_remove(thread_context);
    TEST_CHECK_RET(!uvm_thread_context_present());

    // The removal of a thread context is expected to be the last operation on
    // every UVM module entry point. This test breaks that expectation, so
    // proceed carefully and avoid invoking any function that assumes the
    // presence of the thread context.

    // The loop is used to detect concurrency errors when multiple threads add
    // or remove their contexts to/from global data structures.
    for (i = 0; i < params->iterations; i++) {
        UVM_ENTRY_VOID();
        TEST_CHECK_RET(!uvm_thread_context_present());
    }

    // The restored thread context may be added to an array or tree location
    // different from the original one.
    TEST_CHECK_RET(uvm_thread_context_add(thread_context));

    uvm_thread_context_restore(&thread_context_wrapper_backup.context);

    TEST_CHECK_RET(uvm_thread_context_present());

    return NV_OK;
}