Re: System Load analyze

Hello

maybe you have to tune bgwriter. Please, read this article
http://www.westnet.com/~gsmith/content/postgresql/chkp-bgw-83.htm

Regards
Pavel Stehule

On 25/11/2007, Peter Bauer <peter(dot)bauer(at)apus(dot)co(dot)at> wrote:
>
> Hi all,
>
> i have a system here with 2 2.4GHz Xeon Processors, 2GB RAM, ONE Disk on
> a Battery Backed Write Cache SCSI Controller and PostgreSQL 8.1.4
> running with the data on a DRBD Device for High Availability. The used
> database is also replicated to two similar machines with slony1.
>
> Since the load average is between 1 (most of the time) and 10 (peeks) i
> am worried about the load and executed vmstat and iostat which show that
> 1000-6000 Blocks are writen per second. Please check the attached output
> for further details.
> top shows that the CPUs are at least 80% idle most of the time so i
> think there is an I/O bottleneck. I'm aware that this hardware setup is
> probably not sufficient but is would like to investigate how critical
> the situation is.
>
> thanks,
> Peter
>
>
>
> procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 0 0 398256 78328 140612 1063556 0 0 0 1472 2029 5081 4 3 92 0
> 0 2 398256 78268 140612 1063576 0 0 0 2304 1928 4216 0 2 98 0
> 1 2 398256 78100 140612 1063576 0 0 0 1464 1716 3994 1 3 96 0
> 0 0 398256 78704 140612 1063592 0 0 0 916 1435 3570 5 3 91 0
> 0 0 398256 77876 140612 1063616 0 0 0 0 305 1169 3 1 96 0
> 0 1 398256 79200 140612 1063628 0 0 0 2404 2787 6555 7 6 86 0
> 0 2 398256 79256 140612 1063660 0 0 0 1564 1640 3577 4 2 94 0
> 0 0 398256 79324 140612 1063692 0 0 0 1660 2322 5615 5 2 93 0
> 0 0 398256 78668 140612 1063724 0 0 0 1048 1390 4197 16 13 72 0
> 1 0 398256 79344 140612 1063748 0 0 0 1896 2416 5675 5 5 89 0
> 0 0 398256 79336 140612 1063784 0 0 0 1176 1720 4436 5 3 92 0
> 1 2 398256 79280 140612 1063812 0 0 0 1800 1697 3931 3 3 94 0
> 0 1 398256 79048 140612 1063832 0 0 0 1384 1733 4137 4 2 93 0
> 0 1 398256 78792 140612 1063868 0 0 0 1672 2163 5241 3 2 94 0
> 0 0 398256 77608 140612 1063880 0 0 0 1088 1638 3484 4 2 93 0
> 0 0 398256 79108 140612 1063884 0 0 0 1568 2103 5382 7 5 88 0
> 0 0 398256 79100 140612 1063892 0 0 0 1556 1394 3135 2 1 97 0
> 0 2 398256 79084 140612 1063900 0 0 0 1644 2072 4953 2 0 97 0
> 0 0 398256 79060 140612 1063932 0 0 0 1240 1714 3888 5 2 92 0
> 0 2 398256 79032 140612 1063940 0 0 0 1328 1694 4135 4 2 94 0
> 0 1 398256 78452 140612 1063944 0 0 0 620 925 2824 6 7 87 0
> 0 0 398256 79036 140612 1063956 0 0 0 1196 1293 2954 6 7 87 0
> 0 2 398256 79136 140612 1063964 0 0 0 1736 1959 4494 4 2 94 0
> 0 0 398256 79132 140612 1063964 0 0 0 4 260 1039 1 1 98 0
> 0 0 398256 79052 140612 1063980 0 0 0 2444 3084 6955 6 5 89 0
> 0 2 398256 79060 140612 1063988 0 0 0 948 1146 3616 3 1 96 0
> 0 1 398256 78268 140612 1064056 0 0 0 1908 1809 4086 6 5 88 0
> 0 1 398256 76728 140612 1064056 0 0 0 6256 6637 15472 5 5 90 0
> 0 2 398256 77000 140612 1064064 0 0 0 4916 5840 12107 1 4 95 0
> 0 2 398256 76956 140612 1064068 0 0 0 6468 7432 15211 1 3 96 0
> 0 6 398256 77388 140612 1064072 0 0 0 8116 7826 18265 1 8 91 0
> 0 2 398256 74312 140612 1064076 0 0 0 7032 6886 16136 2 7 91 0
> 0 2 398256 74264 140612 1064076 0 0 0 5680 7143 13411 0 5 95 0
> 0 2 398256 72980 140612 1064140 0 0 0 5396 6377 13251 6 6 88 0
> 0 3 398256 76972 140612 1064148 0 0 0 5652 6793 14079 4 9 87 0
> 0 2 398256 77836 140612 1064148 0 0 0 3968 5321 14187 10 8 82 0
> 1 0 398256 77280 140612 1064148 0 0 0 1608 3188 8974 21 12 67 0
> 1 0 398256 77832 140612 1064152 0 0 0 236 834 2625 7 5 87 0
> 0 0 398256 77464 140612 1064152 0 0 0 244 505 1378 2 4 94 0
> 1 0 398256 77828 140612 1064164 0 0 0 316 580 1954 7 2 91 0
> 0 0 398256 77804 140612 1064180 0 0 0 740 673 2248 2 2 96 0
> 0 0 398256 77000 140612 1064180 0 0 0 304 589 1739 1 3 96 0
> 0 0 398256 77000 140612 1064184 0 0 0 0 216 886 0 1 99 0
> 0 0 398256 75452 140612 1064184 0 0 0 432 755 2032 6 1 93 0
> 0 0 398256 76964 140616 1064200 0 0 0 1980 2722 6452 7 2 91 0
> 0 0 398256 77040 140616 1064212 0 0 0 1524 1536 3635 5 1 93 0
> 0 2 398256 77028 140616 1064216 0 0 0 1136 1489 3342 1 2 97 0
> 0 0 398256 76976 140616 1064236 0 0 0 1392 1831 4468 3 2 94 0
> 0 0 398256 76944 140616 1064256 0 0 0 932 1374 3318 7 8 85 0
> 0 0 398256 76856 140616 1064276 0 0 0 1392 1773 3985 5 4 91 0
> 1 4 398256 76536 140616 1064448 0 0 0 1432 1537 3950 4 2 94 0
> 0 0 398256 76640 140616 1064308 0 0 0 560 865 2577 6 3 91 0
> 0 0 398256 76368 140616 1064328 0 0 0 1752 1973 4424 3 3 94 0
> 0 0 398256 74732 140616 1064340 0 0 0 1244 1807 3758 4 6 90 0
> 1 2 398256 76244 140616 1064352 0 0 0 876 1189 3579 4 2 94 0
> 0 0 398256 76192 140616 1064360 0 0 0 1856 1623 3727 5 4 91 0
> 0 0 398256 76236 140616 1064372 0 0 0 1292 1748 3664 5 4 91 0
> 0 0 398256 76548 140616 1064392 0 0 0 0 338 1810 11 5 84 0
> 0 0 398256 76540 140616 1064392 0 0 0 0 278 1055 2 4 93 0
>
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 241.00 0.00 6344.00 0 6344
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 39.00 0.00 1240.00 0 1240
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 170.00 0.00 3944.00 0 3944
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 173.00 0.00 3880.00 0 3880
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 73.00 0.00 2656.00 0 2656
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 120.00 0.00 2656.00 0 2656
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 81.00 0.00 2184.00 0 2184
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 133.00 0.00 3144.00 0 3144
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 115.00 0.00 2936.00 0 2936
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 64.00 0.00 2080.00 0 2080
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 176.00 0.00 4384.00 0 4384
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 172.00 0.00 3296.00 0 3296
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 191.00 0.00 3880.00 0 3880
> dev8-1 0.00 0.00 0.00 0 0
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> dev8-0 144.00 0.00 2464.00 0 2464
> dev8-1 0.00 0.00 0.00 0 0
>
>
>
> #---------------------------------------------------------------------------
> # FILE LOCATIONS
> #---------------------------------------------------------------------------
>
> # The default values of these variables are driven from the -D command line
> # switch or PGDATA environment variable, represented here as ConfigDir.
>
> data_directory = '/clstsql/data' # btaf: Data Directory on the drbd device, APUS
>
> #hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
> #ident_file = 'ConfigDir/pg_ident.conf' # IDENT configuration file
>
> # If external_pid_file is not explicitly set, no extra pid file is written.
> #external_pid_file = '(none)' # write an extra pid file
>
>
> #---------------------------------------------------------------------------
> # CONNECTIONS AND AUTHENTICATION
> #---------------------------------------------------------------------------
>
> # - Connection Settings -
>
> listen_addresses = '*' # btaf: '*' = Listen to all addresses
> port = 5432 # btaf: Use default port for PostgreSQL, APUS
>
> max_connections = 400 # btaf: APUS
> # note: increasing max_connections costs ~400 bytes of shared memory per
> # connection slot, plus lock space (see max_locks_per_transaction). You
> # might also need to raise shared_buffers to support more connections.
> #superuser_reserved_connections = 2
> unix_socket_directory = '/var/run/postgresql'
> #unix_socket_group = ''
> #unix_socket_permissions = 0777 # octal
> #bonjour_name = '' # defaults to the computer name
>
> # - Security & Authentication -
>
> #authentication_timeout = 60 # 1-600, in seconds
>
> ssl = false # btaf: Do not use ssl for connections, APUS
>
> #password_encryption = on
> #db_user_namespace = off
>
> # Kerberos
> #krb_server_keyfile = ''
> #krb_srvname = 'postgres'
> #krb_server_hostname = '' # empty string matches any keytab entry
> #krb_caseins_users = off
>
> # - TCP Keepalives -
> # see 'man 7 tcp' for details
>
> #tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
> # 0 selects the system default
> #tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
> # 0 selects the system default
> #tcp_keepalives_count = 0 # TCP_KEEPCNT;
> # 0 selects the system default
>
>
> #---------------------------------------------------------------------------
> # RESOURCE USAGE (except WAL)
> #---------------------------------------------------------------------------
>
> # - Memory -
>
> shared_buffers = 40000 # min 16 or max_connections*2, 8KB each, APUS
> temp_buffers = 8000 # min 100, 8KB each, APUS
> #max_prepared_transactions = 5 # can be 0 or more
> # note: increasing max_prepared_transactions costs ~600 bytes of shared memory
> # per transaction slot, plus lock space (see max_locks_per_transaction).
> work_mem = 20480 # min 64, size in KB, APUS
> maintenance_work_mem = 51200 # min 1024, size in KB, APUS
> #max_stack_depth = 2048 # min 100, size in KB
>
> # - Free Space Map -
>
> max_fsm_pages = 40000 # min max_fsm_relations*16, 6 bytes each, APUS
> #max_fsm_relations = 1000 # min 100, ~70 bytes each
>
> # - Kernel Resource Usage -
>
> #max_files_per_process = 1000 # min 25
> #preload_libraries = ''
>
> # - Cost-Based Vacuum Delay -
>
> #vacuum_cost_delay = 0 # 0-1000 milliseconds
> #vacuum_cost_page_hit = 1 # 0-10000 credits
> #vacuum_cost_page_miss = 10 # 0-10000 credits
> #vacuum_cost_page_dirty = 20 # 0-10000 credits
> #vacuum_cost_limit = 200 # 0-10000 credits
>
> # - Background writer -
>
> bgwriter_delay = 100 # 10-10000 milliseconds between rounds, APUS
> bgwriter_lru_percent = 2.0 # 0-100% of LRU buffers scanned/round, APUS
> bgwriter_lru_maxpages = 10 # 0-1000 buffers max written/round, APUS
> bgwriter_all_percent = 1 # 0-100% of all buffers scanned/round, APUS
> bgwriter_all_maxpages = 10 # 0-1000 buffers max written/round, APUS
>
>
> #---------------------------------------------------------------------------
> # WRITE AHEAD LOG
> #---------------------------------------------------------------------------
>
> # - Settings -
>
> #fsync = on # turns forced synchronization on or off
> #wal_sync_method = fsync # the default is the first option
> # supported by the operating system:
> # open_datasync
> # fdatasync
> # fsync
> # fsync_writethrough
> # open_sync
> #full_page_writes = on # recover from partial page writes
> #wal_buffers = 8 # min 4, 8KB each
> #commit_delay = 0 # range 0-100000, in microseconds
> #commit_siblings = 5 # range 1-1000
>
> # - Checkpoints -
>
> checkpoint_segments = 32 # in logfile segments, min 1, 16MB each, APUS
> #checkpoint_timeout = 300 # range 30-3600, in seconds
> checkpoint_warning = 100 # in seconds, 0 is off, APUS
>
> # - Archiving -
>
> #archive_command = '' # command to use to archive a logfile
> # segment
>
>
> #---------------------------------------------------------------------------
> # QUERY TUNING
> #---------------------------------------------------------------------------
>
> # - Planner Method Configuration -
>
> #enable_bitmapscan = on
> #enable_hashagg = on
> #enable_hashjoin = on
> #enable_indexscan = on
> #enable_mergejoin = on
> #enable_nestloop = on
> #enable_seqscan = on
> #enable_sort = on
> #enable_tidscan = on
>
> # - Planner Cost Constants -
>
> effective_cache_size = 89600 # typically 8KB each, APUS
> #random_page_cost = 4 # units are one sequential page fetch
> # cost
> #cpu_tuple_cost = 0.01 # (same)
> #cpu_index_tuple_cost = 0.001 # (same)
> #cpu_operator_cost = 0.0025 # (same)
>
> # - Genetic Query Optimizer -
>
> #geqo = on
> #geqo_threshold = 12
> #geqo_effort = 5 # range 1-10
> #geqo_pool_size = 0 # selects default based on effort
> #geqo_generations = 0 # selects default based on effort
> #geqo_selection_bias = 2.0 # range 1.5-2.0
>
> # - Other Planner Options -
>
> #default_statistics_target = 10 # range 1-1000
> #constraint_exclusion = off
> #from_collapse_limit = 8
> #join_collapse_limit = 8 # 1 disables collapsing of explicit
> # JOINs
>
>
> #---------------------------------------------------------------------------
> # ERROR REPORTING AND LOGGING
> #---------------------------------------------------------------------------
>
> # - Where to Log -
>
> #log_destination = 'stderr' # Valid values are combinations of
> # stderr, syslog and eventlog,
> # depending on platform.
>
> # This is used when logging to stderr:
> #redirect_stderr = off # Enable capturing of stderr into log
> # files
>
> # These are only used if redirect_stderr is on:
> #log_directory = 'pg_log' # Directory where log files are written
> # Can be absolute or relative to PGDATA
> #log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # Log file name pattern.
> # Can include strftime() escapes
> #log_truncate_on_rotation = off # If on, any existing log file of the same
> # name as the new log file will be
> # truncated rather than appended to. But
> # such truncation only occurs on
> # time-driven rotation, not on restarts
> # or size-driven rotation. Default is
> # off, meaning append to existing files
> # in all cases.
> #log_rotation_age = 1440 # Automatic rotation of logfiles will
> # happen after so many minutes. 0 to
> # disable.
> #log_rotation_size = 10240 # Automatic rotation of logfiles will
> # happen after so many kilobytes of log
> # output. 0 to disable.
>
> # These are relevant when logging to syslog:
> #syslog_facility = 'LOCAL0'
> #syslog_ident = 'postgres'
>
>
> # - When to Log -
>
> #client_min_messages = notice # Values, in order of decreasing detail:
> # debug5
> # debug4
> # debug3
> # debug2
> # debug1
> # log
> # notice
> # warning
> # error
>
> #log_min_messages = notice # Values, in order of decreasing detail:
> # debug5
> # debug4
> # debug3
> # debug2
> # debug1
> # info
> # notice
> # warning
> # error
> # log
> # fatal
> # panic
>
> #log_error_verbosity = default # terse, default, or verbose messages
>
> #log_min_error_statement = panic # Values in order of increasing severity:
> # debug5
> # debug4
> # debug3
> # debug2
> # debug1
> # info
> # notice
> # warning
> # error
> # panic(off)
>
> log_min_duration_statement = 1000 # -1 is disabled, 0 logs all statements
> # and their durations, in milliseconds.
>
> #silent_mode = off # DO NOT USE without syslog or
> # redirect_stderr
>
> # - What to Log -
>
> #debug_print_parse = off
> #debug_print_rewritten = off
> #debug_print_plan = off
> #debug_pretty_print = off
> #log_connections = off
> #log_disconnections = off
> #log_duration = off
> log_line_prefix = '[%d %m]' # Special values:
> # %u = user name
> # %d = database name
> # %r = remote host and port
> # %h = remote host
> # %p = PID
> # %t = timestamp (no milliseconds)
> # %m = timestamp with milliseconds
> # %i = command tag
> # %c = session id
> # %l = session line number
> # %s = session start timestamp
> # %x = transaction id
> # %q = stop here in non-session
> # processes
> # %% = '%'
> # e.g. '<%u%%%d> '
> #log_statement = 'none' # none, mod, ddl, all
> #log_hostname = off
>
>
> #---------------------------------------------------------------------------
> # RUNTIME STATISTICS
> #---------------------------------------------------------------------------
>
> # - Statistics Monitoring -
>
> #log_parser_stats = off
> #log_planner_stats = off
> #log_executor_stats = off
> #log_statement_stats = off
>
> # - Query/Index Statistics Collector -
>
> #stats_start_collector = on
> stats_command_string = on
> #stats_block_level = off
> stats_row_level = on
> #stats_reset_on_server_start = off
>
>
> #---------------------------------------------------------------------------
> # AUTOVACUUM PARAMETERS
> #---------------------------------------------------------------------------
>
> autovacuum = on # enable autovacuum subprocess?
> autovacuum_naptime = 30 # time between autovacuum runs, in secs, APUS
> autovacuum_vacuum_threshold = 500 # min # of tuple updates before, APUS
> # vacuum
> autovacuum_analyze_threshold = 250 # min # of tuple updates before, APUS
> # analyze
> autovacuum_vacuum_scale_factor = 0.2 # fraction of rel size before, APUS
> # vacuum
> autovacuum_analyze_scale_factor = 0.1 # fraction of rel size before, APUS
> # analyze
> #autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for
> # autovac, -1 means use
> # vacuum_cost_delay
> #autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
> # autovac, -1 means use
> # vacuum_cost_limit
>
>
> #---------------------------------------------------------------------------
> # CLIENT CONNECTION DEFAULTS
> #---------------------------------------------------------------------------
>
> # - Statement Behavior -
>
> #search_path = '$user,public' # schema names
> #default_tablespace = '' # a tablespace name, '' uses
> # the default
> #check_function_bodies = on
> #default_transaction_isolation = 'read committed'
> #default_transaction_read_only = off
> statement_timeout = 60000 # 0 is disabled, in milliseconds, APUS
>
> # - Locale and Formatting -
>
> #datestyle = 'iso, mdy'
> #timezone = unknown # actually, defaults to TZ
> # environment setting
> #australian_timezones = off
> #extra_float_digits = 0 # min -15, max 2
> #client_encoding = sql_ascii # actually, defaults to database
> # encoding
>
> # These settings are initialized by initdb -- they might be changed
> lc_messages = 'C' # locale for system error message
> # strings
> lc_monetary = 'C' # locale for monetary formatting
> lc_numeric = 'C' # locale for number formatting
> lc_time = 'C' # locale for time formatting
>
> # - Other Defaults -
>
> #explain_pretty_print = on
> #dynamic_library_path = '$libdir'
>
>
> #---------------------------------------------------------------------------
> # LOCK MANAGEMENT
> #---------------------------------------------------------------------------
>
> #deadlock_timeout = 1000 # in milliseconds
> #max_locks_per_transaction = 64 # min 10
> # note: each lock table slot uses ~220 bytes of shared memory, and there are
> # max_locks_per_transaction * (max_connections + max_prepared_transactions)
> # lock table slots.
>
>
> #---------------------------------------------------------------------------
> # VERSION/PLATFORM COMPATIBILITY
> #---------------------------------------------------------------------------
>
> # - Previous Postgres Versions -
>
> add_missing_from = on # btaf: Add missing FROM clauses to improve compatibility with 7.4.x versions
>
> #backslash_quote = safe_encoding # on, off, or safe_encoding
> #default_with_oids = off
> #escape_string_warning = off
> #regex_flavor = advanced # advanced, extended, or basic
> #sql_inheritance = on
>
> # - Other Platforms & Clients -
>
> #transform_null_equals = off
>
>
> #---------------------------------------------------------------------------
> # CUSTOMIZED OPTIONS
> #---------------------------------------------------------------------------
>
> #custom_variable_classes = '' # list of custom variable class names
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
>