I was reading in to the parameter a little more and it appears that the
defuault for vm.overcommit_ratio is 50%, I am considering bumping this
up to 95% so the sums look like this:
max memory allocation for process = swap + ratio of physical memory
21 + (16 * 0.95) = 36.2GB
This in theory should always leave me with roughly 1GB of free physical
memory, swap may be blown though :) (if my understanding of this
parameter is correct).
What I dont understand is, even at its default, the overcommit ratio is
50% of physical, which would make it 21GB + 8GB, ending up at around
29GB (which looks about right in the meminfo output below), so, assuming
my understanding is correct:
[1] How can an analyze process run out of memory on this setting if
it is asking for, at most, maintenance_work_mem (plus some overhead) 128MB
[2] How can a new connection run out of memory, I presume work_mem
+ some overhead, I'm guessing around 2MB memory?
I'm beginning to wonder if my issue is somewhere else now.
Thanks for the tip though at looking at vm.overcommit_ratio, I obvisouly
overlooked this setting when setting vm.overcommit_memory = 2
Any other pointers would be greatly appreciated :)
Reference:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html
Thanks
Bruce
On 16/06/2014 14:21, Bruce McAlister wrote:
Hi,
On 16/06/2014 14:15, Andres Freund wrote:
Hi,
On 2014-06-16 13:56:23 +0100, Bruce McAlister wrote:
[1] 3 x ESX VM's
[a] 8 vCPU's each
[b] 16GB memory each
# Dont hand out more memory than neccesary
vm.overcommit_memory = 2
So you haven't tune overcommit_ratio at all? Can you show
/proc/meminfo's contents?
My guess is that the CommitLimit is too low...
No I have not tune overcommit_ratio.
Below is the /proc/meminfo contents. One note though, the database is
currently not running on this node, just in case i need to make some
changes that require a restart.
[root@bfievdb01 heartbeat]# cat /proc/meminfo
MemTotal: 16333652 kB
MemFree: 2928544 kB
Buffers: 197216 kB
Cached: 1884032 kB
SwapCached: 0 kB
Active: 4638780 kB
Inactive: 1403676 kB
Active(anon): 4006088 kB
Inactive(anon): 7120 kB
Active(file): 632692 kB
Inactive(file): 1396556 kB
Unevictable: 65004 kB
Mlocked: 56828 kB
SwapTotal: 22015984 kB
SwapFree: 22015984 kB
Dirty: 3616 kB
Writeback: 0 kB
AnonPages: 4026228 kB
Mapped: 82408 kB
Shmem: 45352 kB
Slab: 197052 kB
SReclaimable: 106804 kB
SUnreclaim: 90248 kB
KernelStack: 4000 kB
PageTables: 15172 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 30182808 kB
Committed_AS: 4342644 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 7004496 kB
VmallocChunk: 34352726816 kB
HardwareCorrupted: 0 kB
AnonHugePages: 3868672 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 10240 kB
DirectMap2M: 16766976 kB
Thanks
Bruce
