Date: Mon, 20 Mar 2006 16:33:38 -0500 From: Charles Swiger <cswiger@mac.com> To: Miguel <mmiranda@123.com.sv> Cc: freebsd-questions@freebsd.org Subject: Re: setting shmmax for postgres Message-ID: <E9C2296F-F20E-4AF4-A970-203450A4599A@mac.com> In-Reply-To: <441F1E9F.8000408@123.com.sv> References: <441F125F.8030101@123.com.sv> <2F7CD998-9048-4299-BEED-9CA475787B2B@mac.com> <441F1E9F.8000408@123.com.sv>
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On Mar 20, 2006, at 4:29 PM, Miguel wrote: >> Just how much RAM do you have in the machine? I don't think you >> can allocate more than 256MB or so to SysV shared memory without >> tuning the number of KVA pages being allocated to the kernel...? >> Maybe it depends on whether the SysV shmem segments are wired >> down by default or not, I think there's a sysctl which controls >> that. > > I have 3G of RAM OK. You probably want to tune the SGA or whatever Postgres calls it to 512-768 MB, then, but I will happily defer to someone more familiar with that particular database. >> You should revert Postgres back to a more reasonable default >> shared region size for now and rebuild the kernel to increase >> these parameters if you actually have the RAM and the need to do so. >> >> -- >> -Chuck > > what parameters? > I cant find any related in GENERIC Look at NOTES, specificly here: # Set the number of PV entries per process. Increasing this can # stop panics related to heavy use of shared memory. However, that can # (combined with large amounts of physical memory) cause panics at # boot time due the kernel running out of VM space. # # If you're tweaking this, you might also want to increase the sysctls # "vm.v_free_min", "vm.v_free_reserved", and "vm.v_free_target". # # The value below is the one more than the default. # options PMAP_SHPGPERPROC=201 # # Change the size of the kernel virtual address space. Due to # constraints in loader(8) on i386, this must be a multiple of 4. # 256 = 1 GB of kernel address space. Increasing this also causes # a reduction of the address space in user processes. 512 splits # the 4GB cpu address space in half (2GB user, 2GB kernel). # options KVA_PAGES=260 -- -Chuck
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