20 messages in org.freebsd.freebsd-hackersKernel [memory] tweaking question| From | Sent On | Attachments |
|---|---|---|
| Matt | Apr 4, 2005 11:43 am | |
| Devon H. O'Dell | Apr 4, 2005 11:49 am | |
| Marc Olzheim | Apr 4, 2005 11:49 am | |
| Joerg Sonnenberger | Apr 4, 2005 11:51 am | |
| Dan Nelson | Apr 4, 2005 11:55 am | |
| Mike Meyer | Apr 5, 2005 4:50 am | |
| gilles chehade | Apr 5, 2005 4:50 am | |
| Dunceor . | Apr 5, 2005 4:50 am | |
| ra...@redshift.com | Apr 5, 2005 5:25 am | |
| Peter Jeremy | Apr 7, 2005 1:36 am | |
| Stijn Hoop | Apr 7, 2005 1:39 am | |
| ra...@redshift.com | Apr 7, 2005 1:50 am | |
| ra...@redshift.com | Apr 7, 2005 1:51 am | |
| Zera William Holladay | Apr 7, 2005 7:24 am | |
| Robert Watson | Apr 7, 2005 12:08 pm | |
| Michael Shalayeff | Jul 7, 2005 12:08 pm | |
| chaton | Jul 7, 2005 12:08 pm | |
| Juan J. Martínez | Jul 7, 2005 12:10 pm | |
| Juan J. Martínez | Jul 7, 2005 12:10 pm | |
| Mike Meyer | Jul 8, 2005 12:25 pm |
| Subject: | Kernel [memory] tweaking question | |
|---|---|---|
| From: | ra...@redshift.com (ra...@redshift.com) | |
| Date: | Apr 7, 2005 1:50:46 am | |
| List: | org.freebsd.freebsd-hackers | |
Great run down, thanks Peter - I will do more checking in those areas.
Ray
At 06:36 PM 4/7/2005 +1000, Peter Jeremy wrote: | On Tue, 2005-Apr-05 05:26:01 -0700, ra...@redshift.com wrote: | >options SHMALL= | >options SHMMAX= | >options SHMMAXPGS= | >options SHMMIN= | >options SHMMNI= | >options SHMSEG= | | These are all reasonably well documented in sys/conf/NOTES. If you | want more detail, try a SystemV-oriented Unix book | | >I understand these control shared memory and how many semaphores the | >kernel can allocate, | | Close - they only control SystemV shared memory. Sane shared memory | is available via mmap(2). SystemV semaphores are controlled via | SEMxxx options. Posix semaphores are listed as 'experimental'. | | > but I guess what I'm not 100% clear on is how | >the kernel uses these resources when it comes to running something | >like Apache or MySQL on a heavily loaded server. | | These values all define limits on the amount of shared memory | available system-wide (SHMALL and SHMMNI) and to a single process | (remaining options). As far as I can tell, neither Apache nor MySQL | use any SystemV IPC on FreeBSD. (The only thing that I've found that | does use SHM is X in some modes). | | > In other words, for | >something like Apache, how much shared memory is required? | | None. | | > Or what | >would adding additional shared memory and/or semaphores provide. | | Nothing. | | >Does the default # provided for by FreeBSD create a problem and/or | >would it use additional ram if allocated? | | Actually using SystemV IPC will use additional RAM. | | >Is there the anyone on the list that has experience with changing | >these that can provide a clear, down to earth explanation as to their | >impacts? | | I have used them on other Unices but never needed to tweak them on | FreeBSD. Before adjusting anything, use ipcs(1) to confirm that | they are being used. If you seem to be reaching limits (ipcs shows | that you are close to system limits or the applications are reporting | allocation errors), then just increase the parameter related to | whatever you are running out of. | | -- | Peter Jeremy | |