Iloa Semaphore i Linux

O le faaliliuga o le tusiga na saunia i le afiafi o le amataga o le vasega "Fa'atonu Linux.Basic".

O le semaphore o se masini e mafai ai ona faʻaogaina faiga faʻatauvaʻa ma filo e galulue faʻatasi ai ma punaoa fefaʻasoaaʻi ma fesoasoani i le foia o faʻafitauli faʻatasi eseese e pei o tuuga, faʻamaʻi ma filo le amio.

Ina ia foia nei faafitauli, o le fatu o loʻo i ai meafaigaluega e pei o mutexes, semaphores, faailo ma pa puipui.

E tolu ituaiga o semaphore:

1. Binary semaphore
2. Faitauina semaphore
3. Semaphore array (semaphore seti)

Va'ai Tulaga IPC

O tulafono nei e mafai ona faʻaaogaina e maua ai faʻamatalaga e uiga i le tulaga o loʻo i ai nei o fesoʻotaʻiga vaʻavaʻa (IPC).

# ipcs
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest
------ Semaphore Arrays --------

key semid owner perms nsems

------ Message Queues --------
key msqid owner perms used-bytes messages

Fa'asologa semaphore malosi

Fa'aali fa'amatalaga e uiga i fa'asologa o semaphore fa'agaoioia.

# ipcs -s
------ Semaphore Arrays --------
key semid owner perms nsems

Fa'asoa vaega manatua

Va'ai fa'amatalaga e uiga i vaega fa'asoa fa'asoa fa'asoa.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest

Tapulaa

au ipcs -l fa'aali manatu fa'asoa, semaphore ma fe'au tapula'a.

# ipcs -l
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 4194303
max total shared memory (kbytes) = 1073741824
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

------ Messages: Limits --------
max queues system wide = 16
max size of message (bytes) = 65536
default max size of queue (bytes) = 65536

Fa'asoa manatua

O le fa'atonuga o lo'o i lalo o lo'o fa'aalia ai le manatua fa'asoa.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest

Foafoa Punaoa

O le faʻatonuga e faʻaalia ai le tagata faʻaoga ma le vaega o lē e ona ma le na faia le punaoa.

# ipcs -m -c

------ Shared Memory Segment Creators/Owners --------
shmid perms cuid cgid uid gid
65536 600 root root root root
98305 600 root root root root
131074 600 root root root root
163843 600 root root root root
196612 600 root root root root
229381 600 root root root root
262150 600 root root root root
294919 600 root root root root
327688 600 root root root root

Fa'aaogā Meafaigaluega IPC

I le faʻataʻitaʻiga o loʻo i lalo, o le parakalafa -u Fa'aalia se aotelega o le fa'aogaina o meafaigaluega uma IPC.

# ipcs -u

------ Shared Memory Status --------
segments allocated 9
pages allocated 864
pages resident 477
pages swapped 0
Swap performance: 0 attempts 0 successes

------ Semaphore Status --------
used arrays = 0
allocated semaphores = 0

------ Messages: Status --------
allocated queues = 0
used headers = 0
used space = 0 bytes

Pe a taofia auaunaga, e tatau foi ona tape semaphores ma vaega manatua faasoa. Afai e le aveesea, e mafai ona faia lenei mea i le faʻaaogaina o le poloaiga ipcrm, pasia le mea e iloagofie ai le IPC.

# ipcs -a
# ipcrm -s < sem id>

E mafai foi ona e suia tapulaa semaphore i le faaaogaina sysctl.

# /sbin/sysctl -w kernel.sem=250

puna: www.habr.com