1 :Info: an52.errata: errata.an52: System_Metering: 2021-10-29 AN52 Errata
  2 
  3 Function: This info segment provides errata and addenda information for
  4 the Multics manual, AN52-01B titled:
  5 
  6           Multics System Metering
  7 
  8 
  9 change_tuning_parameters:
 10 
 11  pg 4-4, under "Notes":
 12 
 13     DELETE entry for max_abs_eligible (maxabs)
 14 
 15  pg 4-5:
 16 
 17     DELETE entry for double_writes (dblw)
 18 
 19 
 20     CHANGE entry for nto_delta to:
 21 
 22      notify_timeout_interval (nto_delta)
 23        number of seconds
 24        decimal number of seconds
 25        30.0 sec.
 26 
 27     CHANGE entry for nto_severity to:
 28 
 29      notify_timeout_severity (nto_severity)
 30        number of the severity
 31        integer
 32        3
 33 
 34 
 35     CHANGE entry for write_limit to:
 36      write_limit (wlim)
 37        number of pages
 38        integer
 39        1/8 of pageable memory
 40 
 41     CHANGE entry for process_initial_quantum to:
 42      process_initial_quantum (piq)
 43        number of seconds
 44        decimal number of seconds
 45        2.0 sec.
 46 
 47 
 48     ADD (after gv_integration entry) entries for:
 49      max_batch_elig (maxabs)
 50        number of processes
 51        integer
 52        0
 53 
 54      stack_truncation (stkt)
 55        whether to truncate stack on blocking on events if advantageous
 56        boolean value (on or off)
 57        on
 58 
 59      stack_truncation_always (stta)
 60        whether to always truncate stack on blocking on events
 61        boolean value (on or off)
 62        off
 63 
 64 
 65      stk_trunc_block_avg_factor (stk_baf)
 66        factor used in deciding whether to truncate stacks
 67        decimal number
 68        0.9375 (15/16)
 69 
 70      trap_invalid_masked
 71        whether to crash system when invalid mask found when in
 72          user-ring
 73        boolean value (on or off)
 74        off
 75 
 76      meter_ast_locking
 77        whether to meter locking the AST.
 78        boolean value (on or off)
 79        off
 80 
 81 
 82      realtime_io_priority (io_prior)
 83        whether IOI interrupts make process high priority by scheduler
 84        boolean value (on or off)
 85        off
 86 
 87      realtime_io_deadline (io_deadline)
 88        time interval after IOI interrupt process considered high
 89           priority by scheduler
 90        decimal number of seconds
 91        0. seconds
 92 
 93 
 94      realtime_io_quantum (io_quantum)
 95        length of high priority quantum before normal priority
 96          scheduling
 97        decimal number of virtual CPU seconds
 98        0.005 seconds
 99 
100      checksum_filemap
101        whether to checksum the file map to detect integrity issues
102        boolean value (on or off)
103        on
104 
105      default_256K_enable
106        whether 256K segments are allowed for all processes by default
107        boolean value (on or off)
108        off
109 
110 
111      dirlock_writebehind (dirw)
112        causes modified directory pages to be written out
113        boolean value (on or off)
114        off
115 
116 
117  pg 4-7.2, at end, add:
118 
119    The max_batch_elig (maxabs) tuning parameter is the maximum number
120    of absentee processes that can be eligible at one time. A value of
121    zero causes this restriction to be ignored. This parameter is also
122    ignored if the schedule is in deadline mode.
123 
124 
125    The realtime_io_priority, realtime_io_deadling, and
126    realtime_io_quantum tuning parameters jointly control the traffic
127    control priority of a process which has received an interrupt from
128    an IOI device (usually a tape drive).  If realtime_io_priority is
129    off, the parameters realtime_io_deadline and realtime_io_burst have
130    no effect.  The effect of tuning realtime_io_priority on is improved
131    throughput for tape I/O-bound processes (such as the hierarchy and
132    volume dumpers).  This is accomplished by treating a process which
133    has just received an interrupt for an IOI device as a realtime
134    process for one eligibility quantum after receipt of the interrupt.
135    The tuning parameters realtime_io_deadline and realtime_io_quantum
136    control that eligibility time.
137 
138 
139    dirlock_writebehind (dirw) causes modified directory pages to be
140    written from main memory whenever a directory is unlocked.
141    Specifying this parameters increases safety of the system at some
142    cost in increased paging. Process directory pages are not written.
143 
144    See the Multics System Maintenance Procedures Manual, Order No.
145    AM81 for more details on system tuning and tuning parameters.
146 
147 
148 :hcom:
149 /****^  HISTORY COMMENTS:
150   1) change(2021-11-06,Swenson), approve(2021-11-06,MCR10100),
151      audit(2021-11-07,GDixon), install(2021-11-07,MR12.8-1007):
152      Correct and bring up-to-date change_tuning_parameters documentation.
153                                                    END HISTORY COMMENTS */