Re: [HACKERS] xBSD shmem doc deficiency
Hi Neil, > 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 the sysctl is > the kernel option referred to in the docs. Unless this has changed in 4.7, lots of those shm sysctls are read-only...ie. you cannot set the shared memory pool size at runtime. I'll look at it again tho. > (c) the 'prevent shared memory paging' sysctl vaguely referred > to in the docs is 'kern.ipc.shm_use_phys', right? I'll have to investigate that one... Chris ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [HACKERS] xBSD shmem doc deficiency
Neil Conway wrote: > (c) the 'prevent shared memory paging' sysctl vaguely referred > to in the docs is 'kern.ipc.shm_use_phys', right? I have added a mention of this to the 7.4 docs: You might also want to use the sysctl setting to lock shared memory into RAM and prevent it from being paged out to swap, e.g. kern.ipc.shm_use_phys. -- Bruce Momjian| http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup.| Newtown Square, Pennsylvania 19073 ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [HACKERS] xBSD shmem doc deficiency
Apparently only some settings are adjustable. root@dev:~# uname -smr FreeBSD 4.2-RELEASE i386 root@dev:~# sysctl -a | grep kern.ipc.semm kern.ipc.semmap: 30 kern.ipc.semmni: 10 kern.ipc.semmns: 60 kern.ipc.semmnu: 30 kern.ipc.semmsl: 60 root@dev:~# sysctl -w kern.ipc.semmap=50 kern.ipc.semmap: 30 -> 50 root@dev:~# sysctl -w kern.ipc.semmni=50 sysctl: oid 'kern.ipc.semmni' is read only root@dev:~# On 20 Nov 2002, Neil Conway wrote: > 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 maximum size of > shared memory is determined by the option SHMMAXPGS (in > pages). The following shows an example of how to 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 the sysctl 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 <[EMAIL PROTECTED]> || PGP Key ID: DB3C29FC > > > ---(end of broadcast)--- > TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED] > ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] xBSD shmem doc deficiency
On 20 Nov 2002, Neil Conway wrote: > 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 the sysctl is > the kernel option referred to in the docs. > > (b) do the above sysctls work on NetBSD and OpenBSD as well? A quick look at OpenBSD 3.2 (man 3 sysctl) appears to show that all you can do at runtime is enable/disable message queues, shared memory, and semaphores, not adjust buffer counts or sizes. It seems the kernel must still be recompiled with the desired new settings. Jon ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
[HACKERS] xBSD shmem doc deficiency
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 maximum size of shared memory is determined by the option SHMMAXPGS (in pages). The following shows an example of how to 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 the sysctl 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 <[EMAIL PROTECTED]> || PGP Key ID: DB3C29FC ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
