pagecache_hit_miss

Overview

This is a set of tools to monitor the memory used as pagecache.

For now it only has a tool which monitors the pagecache hit/miss

The idea is to add more tools, for example unify the pagecache_ttl (currently in an independent repo) https://github.com/sciclon2/pagecache_ttl

Technical details

The cache hit and miss metric is gathered counting the kernel functions, following the Brendan Gregg idea https://www.brendangregg.com/blog/2014-12-31/linux-page-cache-hit-ratio.html

Using eBPF we track and cound the following Kernel functions:

• mark_page_accessed() for measuring cache accesses
• mark_buffer_dirty() for measuring cache writes
• add_to_page_cache_lru() for measuring page additions
• account_page_dirtied() for measuring page dirties

Dependencies

This tool needs BCC, please follow the instructions bellow: https://github.com/iovisor/bcc/blob/master/INSTALL.md

Installation

Via pip:

foo@bar:~# pip install pagecache_tools

Local in this repository root:

foo@bar:~# pip install -e .

Example

foo@bar:~# /usr/local/bin/pagecache_hit_miss  --help
usage: pagecache_hit_miss [-h] [--interval-seconds INTERVAL_SECONDS]
                          [--daemon] [--send-metrics-to-dogstatsd]
                          [--log-level {INFO,DEBUG}] [--log-file LOG_FILE]

PageCache Hit/Miss

optional arguments:
  -h, --help            show this help message and exit
  --interval-seconds INTERVAL_SECONDS
                        Sets the interval to get the missed/hit values and
                        calculate the avg.
  --daemon              Execute the program in daemon mode.
  --send-metrics-to-dogstatsd
                        Send metrics to local DogStatsD
                        https://docs.datadoghq.com/developers/dogstatsd/
  --log-level {INFO,DEBUG}
                        Sets the log level
  --log-file LOG_FILE   Sets the log file.