gpu-screen-recorder/src/overclock.c

#include "../include/overclock.h"
#include <X11/Xlib.h>
#include <stdio.h>
#include <string.h>

// HACK!!!: When a program uses cuda (including nvenc) then the nvidia driver drops to performance level 2 (memory transfer rate is dropped and possibly graphics clock).
// Nvidia does this because in some very extreme cases of cuda there can be memory corruption when running at max memory transfer rate.
// So to get around this we overclock memory transfer rate (maybe this should also be done for graphics clock?) to the best performance level while GPU Screen Recorder is running.

// TODO: Does it always drop to performance level 2?
// TODO: Also do the same for graphics clock and graphics memory?

// Fields are 0 if not set

typedef struct {
    int perf;

    int nv_clock;
    int nv_clock_min;
    int nv_clock_max;

    int mem_clock;
    int mem_clock_min;
    int mem_clock_max;

    int mem_transfer_rate;
    int mem_transfer_rate_min;
    int mem_transfer_rate_max;
} NVCTRLPerformanceLevel;

#define MAX_PERFORMANCE_LEVELS 12
typedef struct {
    NVCTRLPerformanceLevel performance_level[MAX_PERFORMANCE_LEVELS];
    int num_performance_levels;
} NVCTRLPerformanceLevelQuery;

typedef void (*split_callback)(const char *str, size_t size, void *userdata);
static void split_by_delimiter(const char *str, size_t size, char delimiter, split_callback callback, void *userdata) {
    const char *it = str;
    while(it < str + size) {
        const char *prev_it = it;
        it = memchr(it, delimiter, (str + size) - it);
        if(!it)
            it = str + size;

        callback(prev_it, it - prev_it, userdata);
        it += 1; // skip delimiter
    }
}

// Returns 0 on error
static int xnvctrl_get_memory_transfer_rate_max(gsr_xnvctrl *xnvctrl, const NVCTRLPerformanceLevelQuery *query) {
    NVCTRLAttributeValidValuesRec valid;
    if(xnvctrl->XNVCTRLQueryValidTargetAttributeValues(xnvctrl->display, NV_CTRL_TARGET_TYPE_GPU, 0, 0, NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET_ALL_PERFORMANCE_LEVELS, &valid)) {
        return valid.u.range.max;
    }

    if(query->num_performance_levels > 0 && xnvctrl->XNVCTRLQueryValidTargetAttributeValues(xnvctrl->display, NV_CTRL_TARGET_TYPE_GPU, 0, query->num_performance_levels - 1, NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET, &valid)) {
        return valid.u.range.max;
    }
    
    return 0;
}

static bool xnvctrl_set_memory_transfer_rate_offset(gsr_xnvctrl *xnvctrl, int num_performance_levels, int offset) {
    bool success = false;

    // NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET_ALL_PERFORMANCE_LEVELS works (or at least used to?) without Xorg running as root
    // so we try that first. NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET_ALL_PERFORMANCE_LEVELS also only works with GTX 1000+.
    // TODO: Reverse engineer NVIDIA Xorg driver so we can set this always without root access.
    if(xnvctrl->XNVCTRLSetTargetAttributeAndGetStatus(xnvctrl->display, NV_CTRL_TARGET_TYPE_GPU, 0, 0, NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET_ALL_PERFORMANCE_LEVELS, offset))
        success = true;

    for(int i = 0; i < num_performance_levels; ++i) {
        success |= xnvctrl->XNVCTRLSetTargetAttributeAndGetStatus(xnvctrl->display, NV_CTRL_TARGET_TYPE_GPU, 0, i, NV_CTRL_GPU_MEM_TRANSFER_RATE_OFFSET, offset);
    }

    return success;
}

static void strip(const char **str, int *size) {
    const char *str_d = *str;
    int s_d = *size;

    const char *start = str_d;
    const char *end = start + s_d;

    while(str_d < end) {
        char c = *str_d;
        if(c != ' ' && c != '\t' && c != '\n')
            break;
        ++str_d;
    }

    int start_offset = str_d - start;
    while(s_d > start_offset) {
        char c = start[s_d];
        if(c != ' ' && c != '\t' && c != '\n')
            break;
        --s_d;
    }

    *str = str_d;
    *size = s_d;
}

static void attribute_callback(const char *str, size_t size, void *userdata) {
    if(size > 255 - 1)
        return;

    int size_i = size;
    strip(&str, &size_i);

    char attribute[255];
    memcpy(attribute, str, size_i);
    attribute[size_i] = '\0';

    const char *sep = strchr(attribute, '=');
    if(!sep)
        return;

    const char *attribute_name = attribute;
    size_t attribute_name_len = sep - attribute_name;
    const char *attribute_value_str = sep + 1;

    int attribute_value = 0;
    if(sscanf(attribute_value_str, "%d", &attribute_value) != 1)
        return;

    NVCTRLPerformanceLevel *performance_level = userdata;
    if(attribute_name_len == 4 && memcmp(attribute_name, "perf", 4) == 0)
        performance_level->perf = attribute_value;
    else if(attribute_name_len == 7 && memcmp(attribute_name, "nvclock", 7) == 0)
        performance_level->nv_clock = attribute_value;
    else if(attribute_name_len == 10 && memcmp(attribute_name, "nvclockmin", 10) == 0)
        performance_level->nv_clock_min = attribute_value;
    else if(attribute_name_len == 10 && memcmp(attribute_name, "nvclockmax", 10) == 0)
        performance_level->nv_clock_max = attribute_value;
    else if(attribute_name_len == 8 && memcmp(attribute_name, "memclock", 8) == 0)
        performance_level->mem_clock = attribute_value;
    else if(attribute_name_len == 11 && memcmp(attribute_name, "memclockmin", 11) == 0)
        performance_level->mem_clock_min = attribute_value;
    else if(attribute_name_len == 11 && memcmp(attribute_name, "memclockmax", 11) == 0)
        performance_level->mem_clock_max = attribute_value;
    else if(attribute_name_len == 15 && memcmp(attribute_name, "memTransferRate", 15) == 0)
        performance_level->mem_transfer_rate = attribute_value;
    else if(attribute_name_len == 18 && memcmp(attribute_name, "memTransferRatemin", 18) == 0)
        performance_level->mem_transfer_rate_min = attribute_value;
    else if(attribute_name_len == 18 && memcmp(attribute_name, "memTransferRatemax", 18) == 0)
        performance_level->mem_transfer_rate_max = attribute_value;
}

static void attribute_line_callback(const char *str, size_t size, void *userdata) {
    NVCTRLPerformanceLevelQuery *query = userdata;
    if(query->num_performance_levels >= MAX_PERFORMANCE_LEVELS)
        return;

    NVCTRLPerformanceLevel *current_performance_level = &query->performance_level[query->num_performance_levels];
    memset(current_performance_level, 0, sizeof(NVCTRLPerformanceLevel));
    ++query->num_performance_levels;
    split_by_delimiter(str, size, ',', attribute_callback, current_performance_level);
}

static bool xnvctrl_get_performance_levels(gsr_xnvctrl *xnvctrl, NVCTRLPerformanceLevelQuery *query) {
    bool success = false;
    memset(query, 0, sizeof(NVCTRLPerformanceLevelQuery));

    char *attributes = NULL;
    if(!xnvctrl->XNVCTRLQueryTargetStringAttribute(xnvctrl->display, NV_CTRL_TARGET_TYPE_GPU, 0, 0, NV_CTRL_STRING_PERFORMANCE_MODES, &attributes)) {
        success = false;
        goto done;
    }

    split_by_delimiter(attributes, strlen(attributes), ';', attribute_line_callback, query);
    success = true;

    done:
    if(attributes)
        XFree(attributes);

    return success;
}

bool gsr_overclock_load(gsr_overclock *self, Display *display) {
    memset(self, 0, sizeof(gsr_overclock));
    self->num_performance_levels = 0;

    return gsr_xnvctrl_load(&self->xnvctrl, display);
}

void gsr_overclock_unload(gsr_overclock *self) {
    gsr_xnvctrl_unload(&self->xnvctrl);
}

bool gsr_overclock_start(gsr_overclock *self) {
    int basep = 0;
    int errorp = 0;
    if(!self->xnvctrl.XNVCTRLQueryExtension(self->xnvctrl.display, &basep, &errorp)) {
        fprintf(stderr, "gsr warning: gsr_overclock_start: xnvctrl is not supported on your system, failed to overclock memory transfer rate\n");
        return false;
    }

    NVCTRLPerformanceLevelQuery query;
    if(!xnvctrl_get_performance_levels(&self->xnvctrl, &query) || query.num_performance_levels == 0) {
        fprintf(stderr, "gsr warning: gsr_overclock_start: failed to get performance levels for overclocking\n");
        return false;
    }
    self->num_performance_levels = query.num_performance_levels;

    int target_transfer_rate_offset = xnvctrl_get_memory_transfer_rate_max(&self->xnvctrl, &query) / 2;
    if(query.num_performance_levels > 3) {
        const int transfer_rate_max_diff = query.performance_level[query.num_performance_levels - 1].mem_transfer_rate_max - query.performance_level[2].mem_transfer_rate_max;
        if(transfer_rate_max_diff > 0 && transfer_rate_max_diff < target_transfer_rate_offset)
            target_transfer_rate_offset = transfer_rate_max_diff;
    }

    if(xnvctrl_set_memory_transfer_rate_offset(&self->xnvctrl, self->num_performance_levels, target_transfer_rate_offset)) {
        fprintf(stderr, "gsr info: gsr_overclock_start: sucessfully set memory transfer rate offset to %d\n", target_transfer_rate_offset);
    } else {
        fprintf(stderr, "gsr info: gsr_overclock_start: failed to overclock memory transfer rate offset to %d\n", target_transfer_rate_offset);
    }
    return true;
}

void gsr_overclock_stop(gsr_overclock *self) {
    xnvctrl_set_memory_transfer_rate_offset(&self->xnvctrl, self->num_performance_levels, 0);
}