From 014963008a43808119d9d6c56bbbd1692a4bcb27 Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Tue, 27 Aug 2024 23:50:44 +0200
Subject: process: add taskset, nice

---
 src/process/README.md  |  2 ++
 src/process/nice.md    | 15 +++++++++++++++
 src/process/taskset.md | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 src/process/nice.md
 create mode 100644 src/process/taskset.md

(limited to 'src/process')

diff --git a/src/process/README.md b/src/process/README.md
index 5b07038..8abbdfb 100644
--- a/src/process/README.md
+++ b/src/process/README.md
@@ -6,3 +6,5 @@
 - [ps](./ps.md)
 - [pmap](./pmap.md)
 - [pstack](./pstack.md)
+- [taskset](./taskset.md)
+- [nice](./nice.md)
diff --git a/src/process/nice.md b/src/process/nice.md
new file mode 100644
index 0000000..bda743d
--- /dev/null
+++ b/src/process/nice.md
@@ -0,0 +1,15 @@
+# nice(1)
+
+Adjust `niceness` of a new command or running process.
+
+Niceness influences the scheduling priority and ranges between:
+- `-20` most favorable
+- `19` least favorable
+
+```sh
+# Adjust niceness +5 for the launched process.
+nice -n 5 yes
+
+# Adjust niceness of running process.
+renice -n 5 -p PID
+```
diff --git a/src/process/taskset.md b/src/process/taskset.md
new file mode 100644
index 0000000..aca93b8
--- /dev/null
+++ b/src/process/taskset.md
@@ -0,0 +1,46 @@
+# taskset(1)
+
+Set cpu affinity for new processes or already running ones.
+
+```sh
+# Pin all (-a) tasks of new command on cores 0,1,2,4.
+taskset -ac 0-2,4 CMD [ARGS]
+
+# Pin all tasks of running PID onto cores 0,2,4.
+taskset -ac 0-5:2 -p PID
+```
+
+### Example
+Utility script to extract cpu lists grouped by the last-level-cache.
+```python
+import subprocess
+
+res = subprocess.run(["lscpu", "-p=cpu,cache"], capture_output=True, check=True)
+
+LLC2CPU = dict()
+
+for line in res.stdout.decode().splitlines():
+    if line.startswith("#"):
+        continue
+
+    cpu, cache = line.split(",")
+    llc        = cache.split(":")[-1]
+
+    LLC2CPU.setdefault(llc, list()).append(int(cpu))
+
+LLC2RANGE = dict()
+
+for llc, cpus in LLC2CPU.items():
+    first_cpu = cpus[0]
+    prev_cpu  = cpus[0]
+    for cpu in cpus[1:]:
+        if cpu != prev_cpu + 1:
+            LLC2RANGE.setdefault(llc, list()).append(f"{first_cpu}-{prev_cpu}")
+            # New range begins.
+            first_cpu = cpu
+        prev_cpu = cpu
+    # Trailing range.
+    LLC2RANGE.setdefault(llc, list()).append(f"{first_cpu}-{prev_cpu}")
+
+print(LLC2RANGE)
+```
-- 
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