All Questions
Tagged with performancelinux-kernel
23 questions
1vote
0answers
53views
sysfs missing CPU thermal_throttle information
Background Information: I'm running Ubuntu 24.04.1 LTS (Noble Numbat, kernel 6.8.0-51-generic) on an AMD Ryzen 9 7950X3D, and I'm investigating some odd behavior where the CPU governor/driver will ...
- 11
0votes
0answers
45views
Why only LLC miss ratio increase?
On my server, I have a latency critical (LC) task running on NUMA0. To increase utilization, I have also deployed some best-effort (BE) tasks on the same NUMA0. Furthermore, I have enabled some ...
- 21
2votes
1answer
67views
Why do /dev/ramX devices have all 0's in /proc/diskstats?
Is there away way to turn on IO accounting for /dev/ramX block devices in Linux? I already tried echo 1 > /sys/block/ram1/queue/iostat but it did not work. Notice that all devices have stats except ...
- 515
1vote
0answers
307views
Archlinux, 'kernel.perf_event_paranoid' it not respected
When reading the Performance Counters (PMC) on CPUS, the kernel.perf_event_paranoid must be <=1 (see Kernel doc) The program below reads the PMC and should exit early with 1, if it cannot open the ...
- 161
-3votes
1answer
892views
Why does the Linux kernel not use rust?
I have heard that the Linux Kernel uses rust. I don't know much about the programming language except that it has the potential to run faster than C. According to websites Rust is more safe than C ...
0votes
0answers
602views
Does the worst PCIe MSI interrupt latency jitter over 100us normal?
I try to figure out the values of interrupt jitter in Linux, especially in the worst cases. Two testbeds are considered, one is Raspberry Pi 4B, the other is a high-end PC with an intel i9 CPU and ...
- 111
0votes
1answer
809views
CPU bounded I/O performance issue with NVMe drive on Linux
I have an NVIDIA Jetson TX2 system with an NVMe drive with pcie gen2 x4 speed. The system is running a Linux 4.9 kernel, and I am experiencing issues with write performance. My aim is to write ...
- 101
1vote
1answer
1kviews
How to auto-recompile the Linux Kernel with my hardware-specific needs?
MX Linux 19.2 amd64 - XFCE 4.14 Is there a script or application that detects in-deep all my hardware details, in a manner this auto-configures and recompile the Linux Kernel that works for my current ...
- 459
0votes
0answers
435views
Very high kernel procces time usage in new, idle server
We've recently installed a new server, which shows very high process usage in the kernel - as seen here with htop: the cores and memory are reserved - so the usage is normal - but I've never seen ...
- 77
2votes
1answer
3kviews
How to reduce cache size for radix_tree_node?
Is is possible to reduce the space used for radix_tree_node cache in Linux without reducing overall cache size? For example, I currently have $ sudo slabtop -sc --once | awk '{ if (0 + $1 > 0) { ...
- 4,359
0votes
1answer
789views
Why does rename() take longer when fsync() is called first?
In this test, why does rename() take longer when fsync() is called first? Environment: btrfs, mechanical HDD, Debian 9 container, running on kernel 5.0.17-200.fc29.x86_64. Test command: dpkg -r ...
- 52.8k
0votes
1answer
157views
Performance reduction activating trace-functionality in kernel
Is there any performance reduction to be expected from just activating trace (ftrace) functionality in the Linux kernel, but not using it at run time?
- 381
6votes
1answer
466views
How does the Linux Kernel handle newer chips that patched only against Spectre Variant 1 but not Variant 2?
How will chips patched for Spectre Variant 1 and Meltdown, like Whiskey Lake and Amber Lake, handle Spectre Variant 2? I'm looking to spec out a new laptop. Currently evaluating the Lenovo x390. It's ...
- 34k
2votes
1answer
1kviews
Why is `sync + drop_caches` not dropping caches?
I have a test case for journalctl where it spends several seconds reading from the disk. But if I try to benchmark multiple runs of the test case, I find that it's impossibly fast after the first run....
- 52.8k
1vote
1answer
650views
What can interrupt execution of threads which are pinned to cores?
I do low-latency application development and I use isocpu and set thread affinity to reduce (eliminate?) context switching during my critical threads. However, I am unsure what other types of ...
- 181
