dm-cache/cachestats.sh

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#!/bin/bash
# cachestats for dm-cache
#
# SPDX-License-Identifier: GPL-3.0-or-later
# Copyright 2023 Forza <forza@tnonline.net>
device_name="$1"
# Declare an associative array to store key-value pairs
declare -A data
declare -i sizess
declare status_output
declare -a dmstatus
# Get the status output using dmsetup
status_output=$(dmsetup status "$device_name" 2>/dev/null)
# Check if the device exists and has valid output
if [ -n "$status_output" ]; then
sizess=$(blockdev --getss "/dev/mapper/${device_name}")
# Parse the status information into the associative array
IFS='/: ' read -r -a dmstatus <<< "$status_output"
## Ouput `dmsetup status` raw data:
# for ((i = 0; i < ${#dmstatus[@]}; i += 1)); do
# echo \# $i: ${dmstatus["$i"]}
# done
# Field order of `dmsetup status <cachedev>`:
# https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/cache.html
#
# <metadata block size> <#used metadata blocks>/<#total metadata blocks>
# <cache block size> <#used cache blocks>/<#total cache blocks>
# <#read hits> <#read misses> <#write hits> <#write misses>
# <#demotions> <#promotions> <#dirty> <#features> <features>*
# <#core args> <core args>* <policy name> <#policy args> <policy args>*
# <cache metadata mode>
data["name"]="$device_name"
data["origin_start"]=$(( ${dmstatus[0]} * $sizess )) # in sectors
data["origin_length"]=$(( ${dmstatus[1]} * $sizess )) # in sectors
data["table_type"]="${dmstatus[2]}"
data["metadata_block_size"]=$(( ${dmstatus[3]} * $sizess )) # in sectors
data["used_metadata_blocks"]="${dmstatus[4]}"
data["total_metadata_blocks"]="${dmstatus[5]}"
data["cache_block_size"]=$(( ${dmstatus[6]} * $sizess )) # in sectors
data["used_cache_blocks"]="${dmstatus[7]}"
data["total_cache_blocks"]="${dmstatus[8]}"
data["read_hits"]="${dmstatus[9]}"
data["read_misses"]="${dmstatus[10]}"
data["write_hits"]="${dmstatus[11]}"
data["write_misses"]="${dmstatus[12]}"
data["demotions"]="${dmstatus[13]}"
data["promotions"]="${dmstatus[14]}"
data["dirty_cache"]=$(( ${dmstatus[15]} * ${data[cache_block_size]} ))
if [ "${dmstatus[16]}" = 2 ]; then
data["cache_type"]="${dmstatus[17]}"
data["discard_passdown"]="${dmstatus[18]}"
data["migration_threshold"]=$(( ${dmstatus[21]} * $sizess ))
data["cache_policy"]="${dmstatus[22]}"
data["smq_count"]="${dmstatus[23]}"
data["cache_rw"]="${dmstatus[24]}"
data["status"]="${dmstatus[25]//-/OK}"
else
data["cache_type"]="${dmstatus[17]}"
data["discard_passdown"]="true"
data["migration_threshold"]=$(( ${dmstatus[20]} * $sizess ))
data["cache_policy"]="${dmstatus[21]}"
data["smq_count"]="${dmstatus[22]}"
data["cache_rw"]="${dmstatus[23]}"
data["status"]="${dmstatus[24]//-/OK}"
fi
# Loop through throuh all fields to list and print their values
# for field in "${!data[@]}"; do
# value="${data[$field]}"
# if [ -n "$value" ]; then
# echo "$field : $value"
# else
# echo "Field '$field' not found."
# fi
# done |sort
# Output defined fields
printf "\n"
printf "DEVICE\n"
printf "========\n"
printf "%-*s%s\n" "30" "Device-mapper device: " "${data[name]}"
printf "%-*s%s\n" "30" "Origin size: " "$(( ${data[origin_length]} - ${data[origin_start]} )) bytes"
printf "%-*s%s\n" "30" "Discards: " "${data[discard_passdown]}"
printf "\n"
printf "CACHE\n"
printf "========\n"
printf "%-*s%s\n" "30" "Cache Size: " "$(( ${data[total_cache_blocks]} * ${data[cache_block_size]} )) bytes"
printf "%-*s%s\n" "30" "Cache Usage: " "$(( ${data[used_cache_blocks]} * ${data[cache_block_size]} )) bytes"
printf "%-*s%s\n" "30" "Cache Usage: " "$(( 100 * ${data[used_cache_blocks]} / ${data[total_cache_blocks]} )) %"
printf "%-*s%s\n" "30" "Cache Read Hit: " "${data[read_hits]}"
printf "%-*s%s\n" "30" "Cache Read Miss: " "${data[read_misses]}"
printf "%-*s%s\n" "30" "Cache Write Hit: " "${data[write_hits]}"
printf "%-*s%s\n" "30" "Cache Write Miss: " "${data[write_misses]}"
printf "%-*s%s\n" "30" "Cache Dirty: " "${data[dirty_cache]} bytes"
printf "%-*s%s\n" "30" "Cache Block Size: " "${data[cache_block_size]} bytes"
printf "%-*s%s\n" "30" "Cache Promotions: " "${data[promotions]}"
printf "%-*s%s\n" "30" "Cache Demotions: " "${data[demotions]}"
printf "%-*s%s\n" "30" "Cache Migration Threshold: " "${data[migration_threshold]} bytes"
printf "%-*s%s\n" "30" "Cache RW mode: " "${data[cache_rw]}"
printf "%-*s%s\n" "30" "Cache Type: " "${data[cache_type]}"
printf "%-*s%s\n" "30" "Cache Policy: " "${data[cache_policy]}"
printf "%-*s%s\n" "30" "Cache Status: " "${data[status]}"
printf "\n"
printf "METADATA\n"
printf "========\n"
printf "%-*s%s\n" "30" "Metadata Size: " "$(( ${data[total_metadata_blocks]} * ${data[metadata_block_size]} )) bytes"
printf "%-*s%s\n" "30" "Metadata Usage: " "$(( ${data[used_metadata_blocks]} * ${data[metadata_block_size]} )) bytes"
printf "%-*s%s\n" "30" "Metadata Usage: " "$(( 100 * ${data[used_metadata_blocks]} / ${data[total_metadata_blocks]} )) %"
else
echo "Device not found or no valid status output."
fi