Linux-ck-tt

The Linux-ck-tt kernel and modules with Con Kolivas' hrtimer patches and Task Type CPU scheduler by Hamad Marri and with some other patches. Built on the Linux-ck maintained by graysky.

• Con Kolivas' hrtimer patches and the recommended 1000 Hz tick rate.
• TT-CPU-Scheduler - The goal of the Task Type (TT) scheduler is to detect tasks types based on their behaviours and control the schedulling based on their types. ## fixed for 5.18 by Parvinder Singh.
• kernel_compiler_patch enables compiler optimizations for additional CPUs.
• CJKTTY supports displaying CJK Unified Ideographs on Linux tty.
• BBR v2 is a congestion control algorithm proposed by Google.
• clear from Intel's Clear Linux project. Provides performance and security optimizations.
• bfq-lucjan specific patches authored by Paolo Valente and Piotr Gorski.
• le9 Protect the working set under memory pressure to prevent thrashing, avoid high latency and prevent livelock in near-OOM conditions.

Build and install

Open /etc/pacman.conf and comment out the original Architecture, then add the new Architecture.

#Architecture = auto
Architecture = x86_64 x86_64_v3

Selecting the correct CPU optimized package.

/lib/ld-linux-x86-64.so.2 --help | grep supported

If x86-64-v3 (supported, searched) is in the output, use the Generic-x86-64-v3 (GENERIC_CPU3).

You can compile it yourself and choose the optimization option that suits you.

git clone https://github.com/RiverOnVenus/linux-ck-tt.git

cd linux-ck-tt/linux-ck-tt

updpkgsums && makepkg -srci

You can also download the compiled package.

Clang and DKMS

~~When you use a kernel compiled by CLANG/LLVM/LTO, some modules that use DKMS need to be recompiled with CLANG/LLVM. Otherwise DKMS will fail.~~

~~You need to modify the /etc/dkms/framework.conf file, add two lines to the end of the file: export LLVM=1, export CC=clang.~~

~~If you have done that, just reinstall or install the kernel compiled with CLANG/LLVM/LTO and DKMS will not fail again.~~

Dkms(v3.0.2) support for Clang, use the latest version of dkms and you'll be fine.

Check if TT CPU Scheduler is enabled

This start-up message should appear in the kernel ring buffer when TT in enabled, use:

# dmesg | grep -i 'TT CPU'

You can see: TT CPU scheduler v5.14 by Hamad Al Marri.

Sysctl configuration improving performance

# See https://wiki.archlinux.org/title/Sysctl for more information.

# Networking
net.core.netdev_max_backlog = 16384
net.core.somaxconn = 8192
net.core.rmem_default = 1048576
net.core.rmem_max = 16777216
net.core.wmem_default = 1048576
net.core.wmem_max = 16777216
net.core.optmem_max = 65536
net.ipv4.tcp_rmem = 4096 1048576 2097152
net.ipv4.tcp_wmem = 4096 65536 16777216
net.ipv4.udp_rmem_min = 8192
net.ipv4.udp_wmem_min = 8192
net.ipv4.tcp_fastopen = 3
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 2000000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_fin_timeout = 10
net.ipv4.tcp_mtu_probing = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_rfc1337 = 1
net.ipv4.tcp_keepalive_time = 120
net.ipv4.tcp_keepalive_intvl = 10
net.ipv4.tcp_keepalive_probes = 6
net.ipv4.conf.default.log_martians = 1
net.ipv4.conf.all.log_martians = 1
net.core.default_qdisc = cake

# VFS cache
# Decreasing the virtual file system (VFS) cache parameter value 
# may improve system responsiveness
vm.vfs_cache_pressure = 50

# VM
vm.vfs_cache_pressure = 50
vm.dirty_background_ratio = 25
vm.dirty_ratio = 35
vm.swappiness = 20

# For Solid State Drives
# vm.swappiness = 100
# See https://chrisdown.name/2018/01/02/in-defence-of-swap.html

Changing I/O scheduler if you want

bfq is enabled by default.(bfq-lucjan)

# cat /sys/block/sda/queue/scheduler

To change the active I/O scheduler to bfq for device sda, use:

# echo bfq > /sys/block/sda/queue/scheduler

Or create file /etc/udev/rules.d/60-ioschedulers.rules:

# set scheduler for NVMe
ACTION=="add|change", KERNEL=="nvme[0-9]n[0-9]", ATTR{queue/scheduler}="bfq"
# set scheduler for SSD and eMMC
ACTION=="add|change", KERNEL=="sd[a-z]|mmcblk[0-9]*", ATTR{queue/rotational}=="0", ATTR{queue/scheduler}="bfq"
# set scheduler for rotating disks
ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="1", ATTR{queue/scheduler}="bfq"

Reboot or force udev#Loading new rules:

If rules fail to reload automatically, use:

# udevadm control --reload

To manually force udev to trigger your rules, use:

# udevadm trigger