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'''
Performance Metrics Domain Agent exporting Device Mapper Cache metrics.
'''
#
# Copyright (c) 2014 Red Hat.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
from pcp.pmda import PMDA, pmdaMetric, pmdaIndom, pmdaUnits
from ctypes import POINTER, Structure, cast, c_ulonglong, c_uint
from cpmapi import (PM_SEM_DISCRETE, PM_SEM_INSTANT, PM_SEM_COUNTER,
PM_ERR_INST, PM_ERR_PMID, PM_SPACE_BYTE, PM_SPACE_KBYTE,
PM_TYPE_U32, PM_TYPE_U64, PM_TYPE_STRING, PM_COUNT_ONE)
from subprocess import PIPE, Popen
from os import getenv
IOMODES = { 'writeback': 1, 'writethrough': 2, 'passthrough': 3 }
class DmCacheStats(Structure):
''' Metric values associated with each dm-cache target '''
_fields_ = [("size", c_ulonglong),
("metadata_block_size", c_uint),
("metadata_used", c_ulonglong),
("metadata_total", c_ulonglong),
("cache_block_size", c_uint),
("cache_used", c_ulonglong),
("cache_total", c_ulonglong),
("read_hits", c_uint),
("read_misses", c_uint),
("write_hits", c_uint),
("write_misses", c_uint),
("demotions", c_uint),
("promotions", c_uint),
("dirty", c_ulonglong),
("iomode", c_uint)]
def __init__(self, text):
Structure.__init__(self)
self.parse(text)
def parse(self, line):
'''
Parse an individual line of dmcache statistics text. The format is:
<name>: <start> <end> <target> [Values...]
Values are as in Documentation/device-mapper/cache.txt Status section:
<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>*
'''
data = line.replace('/', ' ').split(' ')
if len(data) < 19:
raise ValueError(line)
mbsize = long(data[4]) * 512 # metadata block size (from sectors)
cbsize = long(data[7]) * 512 # cachedev block size (from sectors)
self.size = long(data[2]) - long(data[1])
self.metadata_block_size = mbsize
self.metadata_used = long(data[5]) * mbsize / 1024
self.metadata_total = long(data[6]) * mbsize / 1024
self.cache_block_size = cbsize
self.cache_used = long(data[8]) * cbsize / 1024
self.cache_total = long(data[9]) * cbsize / 1024
self.read_hits = long(data[10])
self.read_misses = long(data[11])
self.write_hits = long(data[12])
self.write_misses = long(data[13])
self.demotions = long(data[14])
self.promotions = long(data[15])
self.dirty = long(data[16]) * cbsize / 1024
self.iomode = IOMODES[data[18]]
def io_mode(self):
''' Human-readable representation of numeric io_mode encoding '''
for mode in IOMODES:
if self.iomode == IOMODES[mode]:
return mode
return 'unknown'
class DmCachePMDA(PMDA):
'''
Performance Metrics Domain Agent exporting dm-cache module metrics.
Install and make basic use of it, if you use dm-cache, as follows:
# $PCP_PMDAS_DIR/dmcache/Install
$ pminfo -fmdtT dmcache
'''
def __init__(self, name, domain):
'''
Setup metric table (see drivers/md/dm-cache-target.c::cache_status),
the cache devices instance domain, and our callback routines.
'''
PMDA.__init__(self, name, domain)
# dm-cache devices instance domain
self.caches = {}
self.dmstatus = getenv('DM_STATUS', 'dmsetup status --target=cache')
self.cache_indom = self.indom(0)
self.add_indom(pmdaIndom(self.cache_indom, self.caches))
self.set_fetch(self.dmcache_refresh)
self.set_fetch_callback(self.dmcache_fetch_callback)
self.add_metric('dmcache.size',
pmdaMetric(self.pmid(0, 0),
PM_TYPE_U64, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Total size of each cache device (Kbytes)')
self.add_metric('dmcache.metadata.block_size',
pmdaMetric(self.pmid(0, 1),
PM_TYPE_U32, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(1, 0, 0, PM_SPACE_BYTE, 0, 0)),
'Fixed block size for each metadata block in bytes')
self.add_metric('dmcache.metadata.used',
pmdaMetric(self.pmid(0, 2),
PM_TYPE_U64, self.cache_indom, PM_SEM_INSTANT,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Number of metadata blocks used')
self.add_metric('dmcache.metadata.total',
pmdaMetric(self.pmid(0, 3),
PM_TYPE_U64, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Total number of metadata blocks available')
self.add_metric('dmcache.cache.block_size',
pmdaMetric(self.pmid(0, 4),
PM_TYPE_U32, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(1, 0, 0, PM_SPACE_BYTE, 0, 0)),
'Fixed block size for each metadata block in bytes')
self.add_metric('dmcache.cache.used',
pmdaMetric(self.pmid(0, 5),
PM_TYPE_U64, self.cache_indom, PM_SEM_INSTANT,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Number of cache blocks used')
self.add_metric('dmcache.cache.total',
pmdaMetric(self.pmid(0, 6),
PM_TYPE_U64, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Total number of cache blocks available')
self.add_metric('dmcache.read_hits',
pmdaMetric(self.pmid(0, 7),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a READ bio has been mapped to the cache')
self.add_metric('dmcache.read_misses',
pmdaMetric(self.pmid(0, 8),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a READ bio has been mapped to the origin')
self.add_metric('dmcache.write_hits',
pmdaMetric(self.pmid(0, 9),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a WRITE bio has been mapped to the cache')
self.add_metric('dmcache.write_misses',
pmdaMetric(self.pmid(0, 10),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a WRITE bio has been mapped to the origin')
self.add_metric('dmcache.demotions',
pmdaMetric(self.pmid(0, 11),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a block has been removed from the cache')
self.add_metric('dmcache.promotions',
pmdaMetric(self.pmid(0, 12),
PM_TYPE_U32, self.cache_indom, PM_SEM_COUNTER,
pmdaUnits(0, 0, 1, 0, 0, PM_COUNT_ONE)),
'Number of times a block has been moved to the cache')
self.add_metric('dmcache.dirty',
pmdaMetric(self.pmid(0, 13),
PM_TYPE_U64, self.cache_indom, PM_SEM_INSTANT,
pmdaUnits(1, 0, 0, PM_SPACE_KBYTE, 0, 0)),
'Number of blocks in the cache that differ from the origin')
self.add_metric('dmcache.io_mode_code',
pmdaMetric(self.pmid(0, 14),
PM_TYPE_U32, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(0, 0, 0, 0, 0, 0)),
'Cache mode code - writeback, writethrough or passthrough')
self.add_metric('dmcache.io_mode',
pmdaMetric(self.pmid(1, 0),
PM_TYPE_STRING, self.cache_indom, PM_SEM_DISCRETE,
pmdaUnits(0, 0, 0, 0, 0, 0)),
'Cache mode string - writeback, writethrough or passthrough')
def dmcache_refresh(self):
''' Refresh the values and instances for all device mapper caches '''
pipe = Popen(self.dmstatus, shell = True, stdout = PIPE, stderr = PIPE)
output, errors = pipe.communicate()
if errors:
self.err("dmcache_refresh: %s error: %s" % (self.dmstatus, errors))
self.caches.clear()
for line in output.splitlines():
if 'No devices found' in line:
continue
name = line[:line.find(':')] # extract cache name
self.caches[name] = DmCacheStats(line) # extract stats values
self.replace_indom(self.cache_indom, self.caches)
def dmcache_fetch_callback(self, cluster, item, inst):
'''
Look up value associated with requested instance (inst) of a
given metric (cluster:item) PMID, returning a [value,status]
'''
value = self.inst_lookup(self.cache_indom, inst)
if (value == None):
return [PM_ERR_INST, 0]
value = cast(value, POINTER(DmCacheStats))
cache = value.contents
if cluster == 1 and item == 0:
return [cache.io_mode(), 1] # human-readable string encoding
elif cluster != 0:
return [PM_ERR_PMID, 0]
if item == 0:
return [cache.size, 1]
elif item == 1:
return [cache.metadata_block_size, 1]
elif item == 2:
return [cache.metadata_used, 1]
elif item == 3:
return [cache.metadata_total, 1]
elif item == 4:
return [cache.cache_block_size, 1]
elif item == 5:
return [cache.cache_used, 1]
elif item == 6:
return [cache.cache_total, 1]
elif item == 7:
return [cache.read_hits, 1]
elif item == 8:
return [cache.read_misses, 1]
elif item == 9:
return [cache.write_hits, 1]
elif item == 10:
return [cache.write_misses, 1]
elif item == 11:
return [cache.demotions, 1]
elif item == 12:
return [cache.promotions, 1]
elif item == 13:
return [cache.dirty, 1]
elif item == 14:
return [cache.iomode, 1]
return [PM_ERR_PMID, 0]
if __name__ == '__main__':
DmCachePMDA('dmcache', 129).run()
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