系統出現swapped out

[watermelonyu]

我的系統free memory 還有66MB左右

而且process slot還有剩餘

就已經出現swap 現象,請問為什麼呢?





$ sh mem



System Memory Resources on 17-AUG-2005 16:01:35.36







Physical Memory Usage (pages): Total Free In Use Modified



Main Memory (512.00MB) 65536 8516 48618 8402

Slot Usage (slots): Total Free Resident Swapped

Process Entry Slots 356 337 19 0

Balance Set Slots 354 337 17 0

$ sh sys

OpenVMS V8.2 on node VMS82 17-AUG-2005 19:37:07.12 Uptime 0 07:10:32

Pid Process Name State Pri I/O CPU Page flts Pages



00000216 DTLOGIN LEFO 5 -- swapped out -- 28

[watermelonyu]

$moni page



Free List Size 1377.00 1377.84 1377.00 1379.00

Modified List Size 15371.00 15371.00 15371.00 15371.00

modified list size=15371 也還沒超過MPW_HILIMIT=16384,是不是有他因素會造成swap



$ mc sysgen

SYSGEN> SHOW MPW*

Parameter Name Current Default Min. Max. Unit Dynamic

-------------- ------- ------- ------- ------- ---- -------

MPW_WRTCLUSTER 64 64 16 512 Pages

MPW_HILIMIT 16384 512 64 -1 Pages

MPW_LOLIMIT 1062 16 0 -1 Pages

MPW_IOLIMIT 4 4 1 127 I/O

MPW_PRIO 4 4 0 31 D

MPW_THRESH 2124 16 0 -1 Pages D

MPW_WAITLIMIT 16640 576 64 -1 Pages D

MPW_LOWAITLIMIT 16128 448 56 -1 Pages D

[watermelonyu]

MPW_xxx 參數和 swapping 無關, 它們影響的是 paging 和 pagefile usage.



與 swapping 有關的是 MMG_CTLFLAGS, FREELIM 和 FREEGOAL.



FREEGOAL 是 dymamic 的, 您可 online 調整. 調高此參數會發現 swap-out 的 processes 會變多.



這是從 OpenVMS 7.2開始的 "Proactive Memory Reclaimation 功能. 亦即當 FREE MEMORY < FREEGOAL 時就有可能有 process 被 swap-out. 基本上若被 swap-out 的 processes 是不常 active 的就不要去管它!



請看 SYSGEN> HELP SYS_P MMG_CTLFLAGS



Sys_Parameters



MMG_CTLFLAGS



MMG_CTLFLAGS is a bit mask used to enable and disable proactive

memory reclamation mechanisms. Beginning with OpenVMS Version

7.2, you can control when memory is tested. This helps reduce

the time between when you turn on the system and when you log in

to an AlphaServer 4100 computer. Bit 2 in the parameter controls

deferred memory testing.



The following bit mask values are defined:



Bit Description



0 Reclamation enabled by trimming from periodically

executing, but otherwise idle processes. This occurs when

the size of the free list drops below two times FREEGOAL.



1 Reclamation enabled by outswapping processes that have

been idle for longer than LONGWAIT seconds. This occurs

when the size of the free list drops below FREEGOAL.



2 Controls deferred memory testing:



o If the bit is clear (the default), OpenVMS tests

memory in the background and not necessarily before

the bootstrap process has completed.



o If the bit is set, all memory is tested by the end of

EXEC_INIT in the system bootstrap process (that is,

before IPL is lowered from 31).



3-7 Reserved for future use.



MMG_CTLFLAGS is an AUTOGEN and DYNAMIC parameter.