Utangulizi wa Semaphores katika Linux

Tafsiri ya kifungu hicho ilitayarishwa usiku wa kuamkia kozi hiyo "Msimamizi Linux.Msingi".

Semaphore ni utaratibu unaoruhusu michakato na minyororo shindani kushiriki rasilimali na kusaidia na matatizo mbalimbali ya ulandanishi kama vile mbio, kufuli (kufuli kuheshimiana), na nyuzi zinazofanya vibaya.

Ili kutatua shida hizi, kernel hutoa zana kama vile bubu, semaphores, ishara, na vizuizi.

Kuna aina tatu za semaphores:

1. Semaphores za binary
2. Kaunta za semaphores (kuhesabu semaphore)
3. Safu za semaphore (seti ya semaphore)

Tazama hali ya IPC

Amri zifuatazo hutoa taarifa kuhusu hali ya sasa ya mawasiliano baina ya mchakato (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

Safu zinazofanya kazi za semaphores

Onyesha maelezo kuhusu safu amilifu za semaphore.

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

Sehemu za kumbukumbu zilizoshirikiwa

Tazama maelezo kuhusu sehemu za kumbukumbu zinazoshirikiwa.

# 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

Mapungufu

Timu ipcs -l huonyesha kumbukumbu iliyoshirikiwa, semaphore, na mipaka ya ujumbe.

# 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

Kumbukumbu iliyoshirikiwa

Amri hapa chini inaonyesha kumbukumbu iliyoshirikiwa.

# 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

Waundaji Rasilimali

Amri huonyesha mtumiaji na kikundi cha mmiliki na muundaji wa rasilimali.

# 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

Kutumia zana za IPC

Katika mfano hapa chini, parameter -u huonyesha muhtasari wa matumizi ya zana zote za 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

Wakati huduma zimesimamishwa, semaphores na sehemu za kumbukumbu zilizoshirikiwa lazima pia zifutwe. Ikiwa haziondolewa, basi hii inaweza kufanyika kwa kutumia amri ya ipcrm, kupitisha kitambulisho cha kitu cha IPC.

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

Unaweza pia kubadilisha mipaka ya semaphore kwa kutumia sysctl.

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

Chanzo: mapenzi.com