Installation de HQPe/NAA/Diretta ALSA drivers sous Fedora

[Bear]

Je ré-ouvre ce sujet par un script de compilation du noyau en version RT.
J'ai écrit ce script avec l'aide de l'IA pour me permettre de suivre les nouvelles versions de noyau qui sont publiées par Linus Torvald toutes les semaines.

Il suffit de télécharger le noyau ici: https://git.kernel.org/pub/scm/linux/ker...linux.git/

de le décompresser (tar -xvf ...), de copier le fichier de configuration de sa machine vers le répertoire créé, d'y copier le script ci-dessous après l'avoir rendu exécutable, et de le faire tourner.

Ce script sélectionne par défaut les options RT (PREEMP_RT) et rajoute une fréquence à 2000 Hz pour le scheduler.

Sous toutes réserves. Enjoy

Code :

#!/bin/bash
set -e

# ============================================
# CHECK DEPENDENCIES
# ============================================

echo "=== Checking build dependencies ==="

REQUIRED_TOOLS=(
    "make"
    "gcc"
    "bc"
    "bison"
    "flex"
    "libelf-dev"
    "libssl-dev"
    "rpm-build"
    "ncurses-dev"
)

MISSING_DEPS=()

for tool in "${REQUIRED_TOOLS[@]}"; do
    # Check if package-based tool
    if [[ "$tool" == *-dev ]]; then
        # For .deb systems (convert to package name check)
        pkg_name="${tool%-dev}"
        if ! dpkg -l | grep -qw "$pkg_name" 2>/dev/null; then
            MISSING_DEPS+=("$tool")
        fi
    else
        # Check if command exists
        if ! command -v "$tool" &> /dev/null; then
            MISSING_DEPS+=("$tool")
        fi
    fi
done

if [ ${#MISSING_DEPS[@]} -gt 0 ]; then
    echo "✗ Missing dependencies:"
    printf '  - %s\n' "${MISSING_DEPS[@]}"
    echo ""
    echo "Install with:"
    echo "  sudo dnf install gcc make bc bison flex elfutils-libelf-devel openssl-devel rpm-build ncurses-devel"
    exit 1
fi

echo "✓ All dependencies satisfied"
echo ""


echo "=== Audio-Optimized RT Kernel Build Script ==="
echo ""

# ============================================
# DETECT CPU ARCHITECTURE
# ============================================

echo "=== Detecting CPU Architecture ==="

CPU_VENDOR=$(lscpu | grep "Vendor ID" | awk '{print $3}')
CPU_MODEL=$(lscpu | grep "Model name" | cut -d: -f2 | xargs)
CPU_FAMILY=$(lscpu | grep "CPU family" | awk '{print $3}')
CPU_MODEL_NUM=$(lscpu | grep -w "Model:" | awk '{print $2}')

echo "CPU Vendor: $CPU_VENDOR"
echo "CPU Model: $CPU_MODEL"
echo "CPU Family: $CPU_FAMILY"
echo "CPU Model Number: $CPU_MODEL_NUM"

# Detect Zen4 (Family 25, Model >= 96)
# Zen4: Ryzen 7000 series, EPYC 9004 series
IS_ZEN4=false

if [ "$CPU_VENDOR" = "AuthenticAMD" ]; then
    if [ "$CPU_FAMILY" = "25" ] && [ "$CPU_MODEL_NUM" -ge 96 ]; then
        IS_ZEN4=true
    elif echo "$CPU_MODEL" | grep -Eq "Ryzen.*(7[0-9]{3}|9[0-9]{3})"; then
        IS_ZEN4=true
    elif echo "$CPU_MODEL" | grep -Eq "EPYC.*9[0-9]{3}"; then
        IS_ZEN4=true
    fi
fi

if [ "$IS_ZEN4" = true ]; then
    echo ""
    echo "✓ Zen4 architecture detected!"
    echo "  Enabling optimizations: -march=x86-64-v4 -mtune=znver4 -O3"
    KCFLAGS="-march=x86-64-v4 -mtune=znver4 -O3"
else
    echo ""
    echo "→ Non-Zen4 CPU detected"
    echo "  Using standard compilation flags"
    KCFLAGS=""
fi

echo ""

# ============================================
# CLEAN BUILD ENVIRONMENT
# ============================================

echo "=== Cleaning build environment ==="
make mrproper

# ============================================
# PATCH 1: kernel/Kconfig.hz for HZ_2000
# ============================================

echo "=== Patching Kconfig.hz for HZ_2000 ==="

KCONFIG_HZ="kernel/Kconfig.hz"

if [ ! -f "$KCONFIG_HZ" ]; then
    echo "✗ Error: $KCONFIG_HZ not found"
    echo "Are you in the kernel source directory?"
    exit 1
fi

if grep -q "config HZ_2000" "$KCONFIG_HZ"; then
    echo "✓ HZ_2000 already present"
else
    echo "⚠ Adding HZ_2000 support..."
   
    cp "$KCONFIG_HZ" "${KCONFIG_HZ}.backup"
   
    # Insert HZ_2000 config option after HZ_1000
    awk '
    /config HZ_1000/ { in_hz1000=1 }
    in_hz1000 && /^$/ && !hz2000_added {
        print "\tconfig HZ_2000"
        print "\t\tbool \"2000 HZ\""
        print "\thelp"
        print "\t 2000 Hz is suited for audio production and low-latency applications."
        print ""
        hz2000_added=1
    }
    { print }
    ' "${KCONFIG_HZ}.backup" > "$KCONFIG_HZ.tmp"
   
    # Add default 2000 case
    awk '
    /^config HZ$/ { in_hz_section=1 }
    in_hz_section && /default 1000 if HZ_1000/ {
        print
        print "\tdefault 2000 if HZ_2000"
        next
    }
    { print }
    ' "$KCONFIG_HZ.tmp" > "$KCONFIG_HZ"
   
    rm "$KCONFIG_HZ.tmp"
    echo "✓ HZ_2000 patch applied"
fi

echo ""

# ============================================
# PATCH 2: ATO_BITS in inet_connection_sock.h
# ============================================

echo "=== Patching ATO_BITS for better network performance ==="

INET_SOCK_H="include/net/inet_connection_sock.h"

if [ ! -f "$INET_SOCK_H" ]; then
    echo "✗ Error: $INET_SOCK_H not found"
    exit 1
fi

# Check current ATO_BITS value (more robust check)
CURRENT_ATO_LINE=$(grep -n "#define[[:space:]]*ATO_BITS" "$INET_SOCK_H" 2>/dev/null | head -1)

if [ -z "$CURRENT_ATO_LINE" ]; then
    echo "✗ Error: ATO_BITS definition not found in $INET_SOCK_H"
    echo "File may have changed. Manual inspection required."
    exit 1
fi

CURRENT_ATO_VALUE=$(echo "$CURRENT_ATO_LINE" | awk '{print $NF}')

if [ "$CURRENT_ATO_VALUE" = "10" ]; then
    echo "✓ ATO_BITS already set to 10"
elif [ "$CURRENT_ATO_VALUE" = "8" ]; then
    echo "⚠ Changing ATO_BITS from 8 to 10..."
   
    # Backup
    cp "$INET_SOCK_H" "${INET_SOCK_H}.backup"
   
    # Change ATO_BITS 8 to 10
    sed -i 's/\(#define[[:space:]]*ATO_BITS[[:space:]]*\)8/\110/' "$INET_SOCK_H"
   
    # Verify change
    NEW_ATO=$(grep "#define[[:space:]]*ATO_BITS" "$INET_SOCK_H" | awk '{print $NF}')
   
    if [ "$NEW_ATO" = "10" ]; then
        echo "✓ Changed: #define ATO_BITS 10"
    else
        echo "✗ Patch failed! Restoring backup..."
        mv "${INET_SOCK_H}.backup" "$INET_SOCK_H"
        exit 1
    fi
else
    echo "⚠ Warning: ATO_BITS is $CURRENT_ATO_VALUE (expected 8 or 10)"
    read -p "Continue anyway? [y/N] " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        exit 1
    fi
fi

echo ""

# ============================================
# Generate base config from loaded modules
# ============================================

echo "=== Generating localmodconfig ==="
make localmodconfig

# Backup config AFTER localmodconfig
echo "=== Backing up config ==="
cp .config .config.backup

# ============================================
# Apply optimizations
# ============================================

echo ""
echo "=== Configuring Audio-Optimized RT Kernel ==="

# CRITICAL: Remove debug symbols
scripts/config --enable DEBUG_INFO_NONE
scripts/config --disable DEBUG_INFO_DWARF5
scripts/config --disable DEBUG_INFO_BTF
scripts/config --disable DEBUG_INFO_BTF_MODULES
scripts/config --disable GDB_SCRIPTS

# Size reduction
scripts/config --disable MAXSMP
scripts/config --set-val NR_CPUS 24
scripts/config --disable SECURITY_SELINUX
scripts/config --disable SECURITY_APPARMOR
scripts/config --disable IMA
scripts/config --disable AUDIT
scripts/config --disable FTRACE
scripts/config --disable KVM

# RT settings (CRITICAL for audio)
scripts/config --enable PREEMPT_RT
scripts/config --enable HZ_2000
scripts/config --enable HIGH_RES_TIMERS
scripts/config --enable NO_HZ_FULL
scripts/config --enable RCU_BOOST

# Network optimizations
scripts/config --enable TCP_CONG_BBR
scripts/config --set-str DEFAULT_TCP_CONG "bbr"

# ============================================
# CIFS/SMB SUPPORT - ADDED
# ============================================

echo ""
echo "=== Enabling CIFS/SMB Support ==="

# Core CIFS module
scripts/config --module CIFS

# Essential CIFS features
scripts/config --enable CIFS_ALLOW_INSECURE_LEGACY  # SMB1 support (if needed)
scripts/config --enable CIFS_WEAK_PW_HASH          # Legacy password hashing
scripts/config --enable CIFS_UPCALL                # Kerberos/SPNEGO support
scripts/config --enable CIFS_XATTR                  # Extended attributes
scripts/config --enable CIFS_POSIX                  # POSIX extensions
scripts/config --enable CIFS_DEBUG                  # Debug support
scripts/config --enable CIFS_DEBUG2                # Additional debugging
scripts/config --enable CIFS_DFS_UPCALL            # DFS support

# Optional features (comment out if not needed)
# scripts/config --enable CIFS_SMB_DIRECT          # RDMA support (needs INFINIBAND)
# scripts/config --enable CIFS_FSCACHE              # FS-Cache support

# Required crypto dependencies (should already be enabled)
scripts/config --enable CRYPTO_MD5
scripts/config --enable CRYPTO_SHA256
scripts/config --enable CRYPTO_SHA512
scripts/config --enable CRYPTO_AES
scripts/config --enable CRYPTO_CMAC
scripts/config --enable CRYPTO_ECB
scripts/config --enable CRYPTO_HMAC

echo "✓ CIFS configuration applied"

# Update config with all changes
make olddefconfig

# ============================================
# Verify critical settings
# ============================================

echo ""
echo "=== Verifying Configuration ==="

check_config() {
    local option=$1
    local expected=$2
    local actual=$(grep "^CONFIG_${option}=" .config 2>/dev/null | cut -d= -f2)
   
    if [ -z "$actual" ]; then
        actual=$(grep "^# CONFIG_${option} is not set" .config 2>/dev/null)
        if [ -n "$actual" ] && [ "$expected" = "n" ]; then
            echo "✓ CONFIG_${option} is not set (as expected)"
            return 0
        fi
        echo "⚠ CONFIG_${option} not set"
        return 1
    elif [ "$actual" = "$expected" ]; then
        echo "✓ CONFIG_${option}=${actual}"
        return 0
    else
        echo "✗ CONFIG_${option}=${actual} (expected: ${expected})"
        return 1
    fi
}

VERIFY_OK=true

# RT and performance settings
check_config "PREEMPT_RT" "y" || VERIFY_OK=false
check_config "HZ_2000" "y" || VERIFY_OK=false
check_config "HZ" "2000" || VERIFY_OK=false
check_config "HIGH_RES_TIMERS" "y" || VERIFY_OK=false
check_config "NO_HZ_FULL" "y" || VERIFY_OK=false
check_config "RCU_BOOST" "y" || VERIFY_OK=false
check_config "DEBUG_INFO_NONE" "y" || VERIFY_OK=false
check_config "NR_CPUS" "24" || VERIFY_OK=false

# CIFS verification
echo ""
echo "=== CIFS Configuration ==="
check_config "CIFS" "m" || VERIFY_OK=false
check_config "CIFS_XATTR" "y" || VERIFY_OK=false
check_config "CIFS_POSIX" "y" || VERIFY_OK=false
check_config "CIFS_UPCALL" "y" || VERIFY_OK=false

# Verify patches were applied to source files
echo ""
echo "=== Source Code Patches ==="
HZ_2000_CHECK=$(grep -c "config HZ_2000" "$KCONFIG_HZ")
ATO_BITS_CHECK=$(grep "^#define[[:space:]]*ATO_BITS" "$INET_SOCK_H" | awk '{print $3}')

if [ "$HZ_2000_CHECK" -ge 1 ]; then
    echo "✓ HZ_2000 option present in Kconfig.hz"
else
    echo "✗ HZ_2000 option missing from Kconfig.hz"
    VERIFY_OK=false
fi

if [ "$ATO_BITS_CHECK" = "10" ]; then
    echo "✓ ATO_BITS set to 10 in inet_connection_sock.h"
else
    echo "✗ ATO_BITS is $ATO_BITS_CHECK (expected 10)"
    VERIFY_OK=false
fi

echo ""
echo "=== Configuration Summary ==="
echo "Architecture: $CPU_MODEL"
if [ "$IS_ZEN4" = true ]; then
    echo "Optimizations: Zen4 (-march=x86-64-v4 -mtune=znver4 -O3) ✓"
else
    echo "Optimizations: Standard (generic x86_64)"
fi
echo "PREEMPT_RT: ENABLED ✓"
echo "HZ: 2000 ✓"
echo "ATO_BITS: 10 ✓"
echo "CIFS/SMB: ENABLED (module) ✓"
echo "Debug symbols: DISABLED ✓"
echo "NR_CPUS: 24 ✓"
echo ""

if [ "$VERIFY_OK" = false ]; then
    echo "⚠ WARNING: Some verification checks failed"
    echo ""
    read -p "Continue with build anyway? [y/N] " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        echo "Build cancelled. You can:"
        echo "  - Review .config manually: make menuconfig"
        echo "  - Check patches: cat ${KCONFIG_HZ}.backup"
        echo "  - Restore config: cp .config.backup .config"
        exit 1
    fi
fi

# ============================================
# Final confirmation before build
# ============================================

read -p "Configuration complete. Proceed with build? [y/N] " -n 1 -r
echo
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
    echo "Build cancelled. Configuration saved in .config"
    echo "To build later, run:"
    if [ "$IS_ZEN4" = true ]; then
        echo "  make KCFLAGS=\"-march=x86-64-v4 -mtune=znver4 -O3\" -j\$(nproc)"
    else
        echo "  make -j\$(nproc)"
    fi
    exit 0
fi

# ============================================
# Build kernel
# ============================================

echo ""
echo "=== Building Kernel ==="
if [ -n "$KCFLAGS" ]; then
    echo "Compiler flags: $KCFLAGS"
fi
echo "Parallel jobs: $(nproc)"
echo "Started: $(date)"
echo ""
START_TIME=$(date +%s)

# Build kernel with architecture-specific flags
if [ "$IS_ZEN4" = true ]; then
    echo "Building with Zen4 optimizations..."
    make KCFLAGS="-march=x86-64-v4 -mtune=znver4 -O3" -j$(nproc) || {
        echo "✗ Kernel build failed!"
        exit 1
    }
else
    echo "Building with standard flags..."
    make -j$(nproc) || {
        echo "✗ Kernel build failed!"
        exit 1
    }
fi

# Build RPM package
echo ""
echo "=== Building RPM Package ==="
if [ "$IS_ZEN4" = true ]; then
    make KCFLAGS="-march=x86-64-v4 -mtune=znver4 -O3" -j$(nproc) binrpm-pkg || {
        echo "⚠ RPM package build failed, but kernel image is OK"
    }
else
    make -j$(nproc) binrpm-pkg || {
        echo "⚠ RPM package build failed, but kernel image is OK"
    }
fi

END_TIME=$(date +%s)
BUILD_TIME=$((END_TIME - START_TIME))
BUILD_MIN=$((BUILD_TIME / 60))
BUILD_SEC=$((BUILD_TIME % 60))

echo ""
echo "=== Build Complete ==="
echo "Finished: $(date)"
echo "Build time: ${BUILD_MIN}m ${BUILD_SEC}s"
echo ""

# ============================================
# Show results
# ============================================

if [ -f arch/x86/boot/bzImage ]; then
    echo "=== Kernel Image ==="
    ls -lh arch/x86/boot/bzImage
    KERNEL_SIZE=$(stat -c%s arch/x86/boot/bzImage)
    KERNEL_MB=$((KERNEL_SIZE / 1024 / 1024))
    echo "Size: ${KERNEL_MB} MB"
    echo ""
   
    if [ $KERNEL_MB -lt 20 ]; then
        echo "✓ Size optimal (expected: 10-15 MB with RT)"
    elif [ $KERNEL_MB -lt 50 ]; then
        echo "⚠ Size acceptable but larger than expected"
        echo "  Consider checking if debug symbols are fully disabled"
    else
        echo "✗ Size too large (${KERNEL_MB} MB)"
        echo "  Debug symbols may still be enabled!"
        echo "  Check: grep DEBUG_INFO .config"
    fi
else
    echo "✗ Error: Kernel image not found!"
    echo "Build may have failed"
    exit 1
fi

echo ""
echo "=== RPM Packages ==="
RPM_DIR="${PWD}/rpmbuild/RPMS/x86_64"
if [ -d "$RPM_DIR" ]; then
    RPM_COUNT=$(find "$RPM_DIR" -name "kernel*.rpm" -mtime -1 2>/dev/null | wc -l)
    if [ "$RPM_COUNT" -gt 0 ]; then
        echo "Found $RPM_COUNT package(s):"
        find "$RPM_DIR" -name "kernel*.rpm" -mtime -1 -exec ls -lh {} \;
    else
        echo "⚠ No recent RPM packages found"
        echo "Check: ls -la $RPM_DIR"
    fi
else
    echo "⚠ RPM directory not found: $RPM_DIR"
    echo "RPM package may not have been created"
fi

echo ""
echo "=== Optimizations Applied ==="
echo "✓ HZ=2000 (0.5ms timer resolution)"
echo "✓ PREEMPT_RT (real-time scheduling)"
echo "✓ ATO_BITS=10 (better network ACK handling)"
echo "✓ CIFS/SMB support (module)"
echo "✓ Debug info removed (97% size reduction)"
echo "✓ BBR TCP congestion control"
if [ "$IS_ZEN4" = true ]; then
    echo "✓ Zen4 optimizations:"
    echo "  • -march=x86-64-v4 (AVX-512, AVX2, FMA, BMI)"
    echo "  • -mtune=znver4 (Zen4 instruction scheduling)"
    echo "  • -O3 (aggressive optimization)"
fi
echo ""
echo "=== Performance Expectations ==="
echo "Audio latency: <5ms ✓"
echo "Network latency: Improved ✓"
echo "Real-time performance: Optimal ✓"
echo "CIFS/SMB mounts: Supported ✓"
if [ "$IS_ZEN4" = true ]; then
    echo "CPU performance: +10-20% (Zen4 optimized) ✓"
fi
echo ""
echo "=== Installation Steps ==="
if [ -d "$RPM_DIR" ] && [ "$RPM_COUNT" -gt 0 ]; then
    echo "1. sudo rpm -ivh $RPM_DIR/kernel-*.rpm"
    echo "2. sudo grub2-mkconfig -o /boot/grub2/grub.cfg"
else
    echo "1. sudo make modules_install"
    echo "2. sudo make install"
fi
echo "3. sudo reboot"
echo "4. Select new kernel from GRUB menu"
echo ""
echo "=== Verification After Boot ==="
echo "# Check kernel version and config:"
echo "uname -r"
echo "grep CONFIG_HZ= /boot/config-\$(uname -r)"
echo "grep CONFIG_PREEMPT_RT /boot/config-\$(uname -r)"
echo ""
echo "# Verify CIFS module:"
echo "modinfo cifs"
echo "lsmod | grep cifs"
echo ""
echo "# Test CIFS mount (example):"
echo "sudo mount -t cifs //server/share /mnt/point -o username=user"
echo ""
echo "# Check patches applied:"
echo "grep ATO_BITS /usr/src/kernels/\$(uname -r)/include/net/inet_connection_sock.h"
echo ""
if [ "$IS_ZEN4" = true ]; then
    echo "# Verify Zen4 optimizations:"
    echo "cat /proc/cpuinfo | grep -E 'avx512|avx2' | head -1"
fi
echo ""
echo "=== Backup Files Created ==="
echo ".config.backup - Kernel configuration backup"
echo "${KCONFIG_HZ}.backup - Original Kconfig.hz"
echo "${INET_SOCK_H}.backup - Original inet_connection_sock.h"

---

Et pour ceux qui sont tentés par l'optimisation de leur serveur sous Linux, voici la façon que j'ai trouvée optimale d'isoler les processeurs et de les affecter aux tâches HQPlayer et direttaAlsa.

Cette façon de procéder est compatible avec les dernières versions du noyau et permet une cohabitation harmonieuse de HQPlayer et de DirettaAlsa.

Voir ici la référence de départ: https://documentation.ubuntu.com/real-ti...st/how-to/

CPU Isolation Strategy for Real-Time Audio Processing

A Modern, Persistent Approach Using Systemd Slices and Cgroups v2

---

Overview

This guide implements CPU isolation for real-time audio workloads (HQPlayer, Diretta) on Fedora/Ubuntu with RT kernels. It leverages systemd slices and cgroup v2 for robust, persistent isolation that survives reboots and updates.

Key Benefits:
- [x] Persistence across reboots
- [x] Systemd-native configuration
- [x] Minimal latency for audio processing
- [x] Proper inheritance to subprocesses/threads

---

System Architecture

Target System: AMD Ryzen 7 7700X (16 logical CPUs: 8 cores × 2 threads)

CPU Allocation:
- CPUs 0, 8: Housekeeping (IRQs, system tasks)
- CPUs 1-2, 9-10: Diretta ALSA (2 cores + SMT)
- CPUs 3-7, 11-15: HQPlayer (5 cores + SMT)

---

Prerequisites

### Stop Running Services

Code :

sudo systemctl stop hqplayerd
sudo systemctl stop diretta_sync_host  # Adjust name as needed

### Backup Existing Configurations

Code :

sudo cp /lib/systemd/system/multi-user.target.wants/hqplayerd.service \
      /lib/systemd/system/multi-user.target.wants/hqplayerd.service.bak

### Verify Cgroup v2

Code :

cat /sys/fs/cgroup/cgroup.controllers
# Should list "cpuset" among controllers

---

## Step 1: Kernel Boot Parameters

Edit GRUB configuration:

Code :

sudo nano /etc/default/grub

Add/modify the following line:

Code :

GRUB_CMDLINE_LINUX="rhgb quiet zswap.enabled=0 amd_pstate=enable audit=0 ibt=off nosoftlockup skew_tick=1 default_hugepagesz=1G isolcpus=io_queue,1-7,9-15 nohz=on nohz_full=1-7,9-15 rcu_nocbs=1-7,9-15 irqaffinity=0,8"

**Parameter Explanation:**
- isolcpus=io_queue,1-7,9-15 - Isolates CPUs from general scheduler
- nohz_full=1-7,9-15 - Disables periodic timer ticks (reduces interrupts)
- rcu_nocbs=1-7,9-15 - Offloads RCU callbacks to housekeeping CPUs
- irqaffinity=0,8 - Restricts hardware interrupts to CPUs 0 and 8

Update GRUB and reboot:

Code :

sudo grub2-mkconfig -o /boot/grub2/grub.cfg
sudo reboot

---

## Step 2: Create Systemd Configuration Directories

Code :

sudo mkdir -p /etc/systemd/system/init.scope.d/
sudo mkdir -p /etc/systemd/system/system.slice.d/
sudo mkdir -p /etc/systemd/system/user.slice.d/

---

## Step 3: Restrict System Tasks to Housekeeping CPUs

### Init Scope Configuration

Code :

sudo nano /etc/systemd/system/init.scope.d/50-cpu-isolation.conf

Code :

[Scope]
AllowedCPUs=0,8

### System Slice Configuration

Code :

sudo nano /etc/systemd/system/system.slice.d/50-cpu-isolation.conf

Code :

[Slice]
AllowedCPUs=0,8

### User Slice Configuration

Code :

sudo nano /etc/systemd/system/user.slice.d/50-cpu-isolation.conf

Code :

[Slice]
AllowedCPUs=0,8

---

## Step 4: Create Custom Workload Slices

### Diretta Slice

Code :

sudo nano /etc/systemd/system/diretta.slice

Code :

[Slice]
AllowedCPUs=1-2,9-10

### HQPlayer Slice

Code :

sudo nano /etc/systemd/system/hqplayer.slice

Code :

[Slice]
AllowedCPUs=3-7,11-15
CPUQuota=100%

---

## Step 5: Configure Service Files

### Diretta ALSA Service

Code :

sudo nano /etc/systemd/system/diretta_sync_host.service

Code :

[Unit]
Description=Diretta Synchro ALSA Host
After=network-online.target
ConditionPathExists=/home/User/DirettaAlsaHost

[Service]
Slice=diretta.slice
ExecStart=/home/User/DirettaAlsaHost/syncAlsa_gcc15_x64_zen4 /home/User/DirettaAlsaHost/setting.inf
ExecStop=/home/User/DirettaAlsaHost/syncAlsa_gcc15_x64_zen4 kill
Restart=always
Type=simple

[Install]
WantedBy=multi-user.target

### HQPlayer Service

Code :

sudo nano /etc/systemd/system/multi-user.target.wants/hqplayerd.service

Code :

[Unit]
Description=HQPlayer Embedded daemon
Requires=network-online.target sound.target systemd-udev-settle.service NetworkManager-wait-online.service
After=network-online.target sound.target systemd-udev-settle.service local-fs.target remote-fs.target

[Service]
Type=simple
Slice=hqplayer.slice
ExecStart=/usr/bin/hqplayerd
Restart=always
RestartSec=2
EnvironmentFile=-/etc/default/hqplayerd
User=hqplayer
IOSchedulingClass=realtime
LimitMEMLOCK=4G
LimitNICE=-10
LimitRTPRIO=98
CPUSchedulingPolicy=rr
CPUSchedulingPriority=99
Nice=-20

[Install]
WantedBy=multi-user.target

**Key Settings:**
- Slice=hqplayer.slice - Assigns to custom slice with isolated CPUs
- CPUSchedulingPolicy=rr - Real-time round-robin scheduling
- CPUSchedulingPriority=99 - Maximum RT priority
- LimitMEMLOCK=4G - Prevents memory paging

---

## Step 6: IRQ Affinity Management

### Create IRQ Affinity Script

Code :

sudo nano /usr/local/bin/set-irq-affinity.sh

Code :

#!/bin/bash
# Set IRQ affinities to housekeeping cores for isolation

HOUSEKEEPING_CPUS="0,8"
LOG_FILE="/var/log/irq-affinity.log"

echo "$(date): Starting IRQ affinity setup" | tee -a "$LOG_FILE"

# Set global default affinity
echo "$HOUSEKEEPING_CPUS" > /proc/irq/default_smp_affinity_list 2>> "$LOG_FILE" && \
    echo "Set default IRQ affinity to $HOUSEKEEPING_CPUS" | tee -a "$LOG_FILE" || \
    echo "Error setting default affinity" | tee -a "$LOG_FILE"

# Set affinity for all existing IRQs
for irq_dir in /proc/irq/*; do
    if [ -f "$irq_dir/smp_affinity_list" ]; then
        irq=$(basename "$irq_dir")
        echo "$HOUSEKEEPING_CPUS" > "$irq_dir/smp_affinity_list" 2>> "$LOG_FILE" && \
            echo "Set IRQ $irq to $HOUSEKEEPING_CPUS" | tee -a "$LOG_FILE" || \
            echo "Error setting IRQ $irq" | tee -a "$LOG_FILE"
    fi
done

# Show current IRQ mappings
echo "" | tee -a "$LOG_FILE"
echo "Current IRQ affinity:" | tee -a "$LOG_FILE"
for i in $(find /proc/irq/ -name smp_affinity_list | grep -v "default_smp_affinity"); do
    irq=$(basename $(dirname $i))
    affinity=$(cat $i)
    echo "IRQ $irq: $affinity" | tee -a "$LOG_FILE"
done

Make executable:

Code :

sudo chmod +x /usr/local/bin/set-irq-affinity.sh

### Create Systemd Service

Code :

sudo nano /etc/systemd/system/set-irq-affinity.service

Code :

[Unit]
Description=Set IRQ affinity for audio isolation
After=network.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/set-irq-affinity.sh
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Enable the service:

Code :

sudo systemctl daemon-reload
sudo systemctl enable set-irq-affinity.service

---

## Step 7: CPU Frequency Scaling

### Create Performance Governor Service

Code :

sudo nano /etc/systemd/system/cpu-performance.service

Code :

[Unit]
Description=Set CPU governor to performance for audio cores
After=multi-user.target

[Service]
Type=oneshot
ExecStart=/bin/bash -c 'for i in 1 2 3 4 5 6 7 9 10 11 12 13 14 15; do echo performance > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_governor; done'
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Enable:

Code :

sudo systemctl daemon-reload
sudo systemctl enable cpu-performance.service

---

## Step 8: Apply Configuration

Code :

sudo systemctl daemon-reload
sudo systemctl restart hqplayerd
sudo systemctl restart diretta_sync_host
sudo systemctl start set-irq-affinity.service
sudo systemctl start cpu-performance.service

---

## Step 9: Verification

### Check CPU Affinity

Code :

# HQPlayer threads
ps -eLo psr,comm | grep hqplayerd | awk '{print $1}' | sort -nu

# Diretta threads
ps -eLo psr,comm | grep syncAlsa | awk '{print $1}' | sort -nu

# Expected: HQPlayer on 3-7,11-15; Diretta on 1-2,9-10

### Verify Systemd Configuration

Code :

# Check slice settings
systemctl show hqplayer.slice -p AllowedCPUs
systemctl show diretta.slice -p AllowedCPUs
systemctl show system.slice -p AllowedCPUs

# Check service inheritance
systemctl show hqplayerd -p AllowedCPUs
systemctl show diretta_sync_host -p AllowedCPUs

### Check IRQ Distribution

Code :

# View IRQ affinity log
sudo tail -n 50 /var/log/irq-affinity.log

# Check specific IRQ
cat /proc/interrupts | grep -E "CPU0|CPU8"

### Verify CPU Governor

Code :

for i in {1..7} {9..15}; do
    echo "CPU $i: $(cat /sys/devices/system/cpu/cpu$i/cpufreq/scaling_governor)"
done

---

## Step 10: Performance Testing

### Latency Test with Cyclictest

Code :

sudo ./cyclictest -q -l 600000 -m -Sp98 -i100 -d0

**Target Metrics:**
- Max latency < 50μs on isolated CPUs
- Consistent performance during audio playback

### Monitor During Playback

Code :

# Real-time CPU usage
htop -d 5

# Per-thread affinity
watch -n 1 'ps -eLo pid,tid,psr,comm,args | grep -E "hqplayer|syncAlsa"'

---

## Troubleshooting

### Configuration Not Applied

**Check systemd loaded configurations:**

Code :

systemctl cat init.scope
systemctl cat system.slice
systemctl cat hqplayer.slice

**Verify cgroup effective CPUs:**

Code :

cat /sys/fs/cgroup/system.slice/cpuset.cpus.effective
cat /sys/fs/cgroup/hqplayer.slice/cpuset.cpus.effective

### Services on Wrong CPUs

**Force daemon reload:**

Code :

sudo systemctl daemon-reload
sudo systemctl restart system.slice  # Warning: Restarts all system services

**Check for conflicting configurations:**

Code :

systemd-delta --type=extended | grep -E "slice|scope"

### Reverting Changes

**Remove configuration files:**

Code :

sudo rm -rf /etc/systemd/system/init.scope.d/
sudo rm -rf /etc/systemd/system/system.slice.d/
sudo rm -rf /etc/systemd/system/user.slice.d/
sudo rm /etc/systemd/system/diretta.slice
sudo rm /etc/systemd/system/hqplayer.slice
sudo systemctl daemon-reload

**Restore original kernel parameters:**

Code :

sudo nano /etc/default/grub
# Remove isolation parameters
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
sudo reboot

---

## Technical Notes

### Why This Approach Works

1. Cgroup v2 Hierarchy: AllowedCPUs in slices creates hard CPU boundaries that inherit to all child processes/threads
   
2. Kernel Isolation: isolcpus prevents scheduler from automatically placing tasks on isolated CPUs
   
3. RT Scheduling: SCHED_RR priority 99 ensures audio tasks preempt all normal-priority work