Brendan Gregg

AUGUST 29, 2021

A service team was debugging a performance issue and noticed it coincided with a high rate of paging. A cloud-wide monitoring tool, Atlas, showed a high rate of paging for the larger file uploads: The blue is pageins (page ins). 1072-aws (xxx) 12/18/2018 _x86_64_ (16 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 5.03

Cache 105

Cache C++ AWS Latency 105

Brendan Gregg

JULY 2, 2021

This does require at least Linux 5.8 Note that not all Linux distributions have enabled CONFIG_DEBUG_INFO_BTF=y, which is necessary for the future of BTF and CO-RE. cachestat File system cache statistics line charts. A tool may work on Linux 5.3 We've been doing lots of work to fix this in the future. That's the fast way.

Latency 145

Latency Cache Energy Systems 145

Brendan Gregg

AUGUST 29, 2021

A service team was debugging a performance issue and noticed it coincided with a high rate of paging. I was asked to help, and used a variety of Linux performance tools to solve this including those that use eBPF and Ftrace. Pageins are a type of disk I/O where a page of memory is read in from disk, and are normal for many workloads.

Cache 40

Cache C++ AWS Systems 40

Brendan Gregg

JULY 2, 2021

This does require at least Linux 5.8 Note that not all Linux distributions have enabled CONFIG_DEBUG_INFO_BTF=y, which is necessary for the future of BTF and CO-RE. cachestat File system cache statistics line charts 7. Porting them to a different language and then not maintaining them may be like trying to apply a Linux 4.15

Open Source 40

Open Source Latency Cache Energy 40