Gabatarwa zuwa Semaphores a cikin Linux

An shirya fassarar labarin a jajibirin fara karatun "Mai sarrafa Linux.Basic".

Semaphore wata hanya ce da ke ba da damar tafiyar matakai da zaren gasa don raba albarkatu kuma suna taimakawa tare da matsalolin aiki tare daban-daban kamar tsere, makullai (kulle juna), da zaren rashin ɗabi'a.

Don magance waɗannan matsalolin, kernel yana samar da kayan aiki kamar su lanƙwasa, semaphores, sigina, da shinge.

Akwai nau'ikan semaphores guda uku:

1. Binary semaphores
2. Semaphores-counters (ƙidaya semaphore)
3. Arrays na semaphores (semaphore set)

Duba Matsayin IPC

Umurnai masu zuwa suna ba da bayani game da yanayin sadarwa na zamani (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

Tsarukan aiki na semaphores

Nuna bayanai game da tsararrun semaphore masu aiki.

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

Raba sassan ƙwaƙwalwar ajiya

Duba bayani game da ɓangarorin žwažwalwar ajiya mai aiki.

# 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

Iyaka

tawagar ipcs -l yana nuni da žwažwalwar ajiya, semaphore, da iyakokin sažo.

# 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

Ƙwaƙwalwar ajiya

Umurnin da ke ƙasa yana nuna ƙwaƙwalwar ajiyar da aka raba.

# 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

Masu ƙirƙirar albarkatu

Umurnin yana nuna mai amfani da ƙungiyar mai shi da mahaliccin albarkatun.

# 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

Yi amfani da kayan aikin IPC

A cikin misalin da ke ƙasa, siga -u yana nuna taƙaitaccen amfani da duk kayan aikin 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

Lokacin da aka dakatar da sabis, dole ne a share semaphores da ɓangarorin ƙwaƙwalwar ajiya. Idan ba a cire su ba, to ana iya yin wannan ta amfani da umarnin ipcrm, wucewa mai gano abin IPC.

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

Hakanan zaka iya canza iyakokin semaphore ta amfani da sysctl.

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

source: www.habr.com