how to speed up thrashing system
https://chatgpt.com/share/670ae8d7-5908-800e-9002-9c5dd032e138
{
"timestamp": "2024-10-12T21:32:14.607Z",
"conversation": [
{
"r": "user",
"t": "is there a way in linux to reduce something being swapped out so it
can be more responsive, when there is a little thrashing going on?"
},
{
"r": "assistant",
"t": "Yes, you can reduce swap usage to make your system more responsive
during times of minor thrashing by adjusting a few parameters and prioritizing
swap behavior:\n\n### 1. Adjust Swappiness\n\nSwappiness controls how
aggressively the kernel swaps out memory. It ranges from 0 (swap only when
absolutely necessary) to 100 (swap frequently).Lowering swappiness can reduce
how much the system swaps. A value of 10 or 20 is often suitable for desktops
and laptops.To adjust swappiness temporarily:```\nbash\nCopy code\nsudo sysctl
vm.swappiness=10\n\n```\nTo make it permanent, add or modify the following line
in /etc/sysctl.conf:```\nbash\nCopy code\nvm.swappiness=10\n\n```\nThen apply
the change with:```\nbash\nCopy code\nsudo sysctl -p\n\n```\n### 2. Use
vfs_cache_pressure\n\nThis parameter controls the tendency of the kernel to
reclaim the memory used for caching directory and inode objects. Lowering it
can help keep your frequently accessed files in memory.Set it to a lower value
(e.g., 50) to prioritize cached objects in memory:```\nbash\nCopy code\nsudo
sysctl vm.vfs_cache_pressure=50\n\n```\nTo make it permanent, add it to
/etc/sysctl.conf:```\nbash\nCopy code\nvm.vfs_cache_pressure=50\n\n```\n### 3.
Prioritize Specific Processes with ionice\n\nUse ionice to give certain
processes higher I/O priority, which can help with
responsiveness:```\nbash\nCopy code\nsudo ionice -c 1 -p <PID>\n\n```\nReplace
<PID> with the process ID of the program you want to prioritize. Class 1 is
high priority, 2 is normal, and 3 is idle.### 4. Reduce Cache Usage in
Applications\n\nSome applications have settings to control their memory usage.
You can check the documentation for specific software if they allow you to
limit the cache, which can free up memory for more essential tasks.### 5.
Monitor and Kill Thrashing Processes\n\nUse top, htop, or iotop to identify
processes that are causing high disk I/O and memory usage, and then kill them
if necessary:```\nbash\nCopy code\nsudo kill -9 <PID>\n\n```\nBy tweaking these
settings, you can help your Linux system be more responsive, even when there is
some swapping going on.\n\n4o"
},
{
"r": "user",
"t": "ionice helped some, but i think it is still pagefaulting my
foreground process a lot for my memory-hungry background process. any other
ideas?"
},
{
"r": "assistant",
"t": "If ionice helped but your foreground process is still experiencing
significant page faults due to a memory-hungry background process, you can try
a few other approaches to reduce memory contention and prioritize memory for
your active tasks:\n\n### 1. Use oom_score_adj to Deprioritize the Background
Process\n\nThe Out-Of-Memory (OOM) killer can deprioritize certain processes
for memory allocation. By increasing the oom_score_adj value of your background
process, you can make it a candidate for being killed when memory is low.Set
oom_score_adj for the background process (range is from -1000 to 1000, with
higher values being more likely to be targeted):```\nbash\nCopy code\necho 500
| sudo tee /proc/<PID>/oom_score_adj\n\n```\nReplace <PID> with the process ID
of the background process. This way, the kernel is more likely to free up
memory from this process first.### 2. Use cgroups to Limit Memory
Usage\n\nCgroups (control groups) allow you to limit the resources (like
memory) that a process or group of processes can use.Create a cgroup for the
background process and set a memory limit:```\nbash\nCopy code\nsudo cgcreate
-g memory:/background\necho <memory_limit_in_bytes> | sudo tee
/sys/fs/cgroup/memory/background/memory.limit_in_bytes\n\n```\nReplace
<memory_limit_in_bytes> with the desired memory limit. For example, 500M for
500 MB.Then move the background process to this cgroup:```\nbash\nCopy
code\nsudo cgclassify -g memory:background <PID>\n\n```\nYou can install
cgroup-tools if cgcreate and cgclassify aren’t available on your system.### 3.
Use nice to Lower CPU Priority of the Background Process\n\nAlthough it’s more
related to CPU, lowering the background process’s CPU priority with nice can
also reduce the rate of page faults in the foreground process by giving it more
CPU time.Start or change the priority of the background process:```\nbash\nCopy
code\nsudo renice 19 -p <PID>\n\n```\nThe higher the nice value, the lower the
CPU priority, with 19 being the lowest.### 4. Increase vm.min_free_kbytes to
Avoid Heavy Swapping\n\nAdjusting vm.min_free_kbytes will reserve more memory
as a buffer for the system to avoid swapping.For example, setting it to 200000
(200 MB) can help with keeping more memory available:```\nbash\nCopy code\necho
200000 | sudo tee /proc/sys/vm/min_free_kbytes\n\n```\nTo make it persistent,
add vm.min_free_kbytes=200000 to /etc/sysctl.conf.### 5. Use chrt to Adjust the
Scheduling Policy\n\nIf the background process is using real-time scheduling,
it can cause contention. Use chrt to adjust its scheduling policy and
deprioritize it.Change the scheduling policy to SCHED_IDLE (idle
priority):```\nbash\nCopy code\nsudo chrt -i 0 -p <PID>\n\n```\n### 6. Set
Process-Specific Memory Priority with numactl (NUMA Systems)\n\nOn NUMA
systems, you can bind a memory-hungry process to a specific NUMA node to reduce
its impact on other processes.To limit the background process to specific NUMA
nodes:```\nbash\nCopy code\nnumactl --cpubind=1 --membind=1
<command>\n\n```\nReplace 1 with the node you want to bind it to. You can find
available nodes with numactl --hardware.By combining these techniques, you
should be able to isolate the impact of the background process on your
foreground process, making it more responsive.\n\n4o"
}
]
}
