xBSD shmem doc deficiency
От | Neil Conway |
---|---|
Тема | xBSD shmem doc deficiency |
Дата | |
Msg-id | 871y5f4jf4.fsf@mailbox.samurai.com обсуждение исходный текст |
Ответы |
Re: xBSD shmem doc deficiency
Re: xBSD shmem doc deficiency Re: xBSD shmem doc deficiency |
Список | pgsql-hackers |
The documentation on changing shared memory kernel settings on xBSD (namely FreeBSD, possibly others as well) isn't ideal, IMHO. It says: %% The options SYSVSHM and SYSVSEM need to be enabled when the kernel is compiled. (They are by default.) The maximumsize of shared memory is determined by the option SHMMAXPGS (in pages). The following shows an example of howto set the various parameters: options SYSVSHM options SHMMAXPGS=4096 options SHMSEG=256 options SYSVSEM options SEMMNI=256 options SEMMNS=512 options SEMMNU=256 options SEMMAP=256 (On NetBSD and OpenBSD the key word is actually option singular.) You may also want to use the sysctl setting to lock shared memory into RAM and prevent it from being paged out to swap. %% However, it appears that shared memory & semaphore settings can also be controlled via sysctls -- at least on a FreeBSD 4.7-RELEASE box, I can see: kern.ipc.semmap: 30 kern.ipc.semmni: 10 kern.ipc.semmns: 60 kern.ipc.semmnu: 30 kern.ipc.semmsl: 60 kern.ipc.semopm: 100 kern.ipc.semume: 10 kern.ipc.semusz: 92 kern.ipc.semvmx: 32767 kern.ipc.semaem: 16384 kern.ipc.shmmax: 33554432 kern.ipc.shmmin: 1 kern.ipc.shmmni: 192 kern.ipc.shmseg: 128 kern.ipc.shmall: 8192 kern.ipc.shm_use_phys: 0 However, the FreeBSD box I'm playing with isn't mine, so I'm not too keen to change sysctls (well, that and I don't have root :-) ). Would a kind BSD user confirm that: (a) the sysctls above *can* be used to change kernel shared memory settings, and the default value of thesysctl is the kernel option referred to in the docs. (b) do the above sysctls work on NetBSD and OpenBSD as well? (c) the 'prevent shared memory paging' sysctl vaguely referred to in the docs is 'kern.ipc.shm_use_phys',right? (d) does the above sysctl also work on NetBSD and OpenBSD? Thanks in advance, Neil -- Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC
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