Hi List,
I'm tuning up a new database server and I'm finding very mixed
information online.
Here are the default shmmax and shmall from my new system
cat /proc/sys/kernel/shmmax
4294967295
cat /proc/sys/kernel/shmall
268435456
SHMALL is close enough to being SHMMAX / 16.
Now, everything I'm finding online tells me that SHMALL = SHMMAX /
PAGE_SIZE. default page size is 4096.
Has something changed in this calculation? should the defaults be set on
SHMALL = SHMMAX / 16??
I'm running CentOS Linux release 7.1.1503 (Core), my old database is
running CentOS release 6.6 (Final) and I'm seeing the same calculations
there too.
Can somebody please point me in the right direction, I've had a look at
pgtune here http://pgtune.leopard.in.ua/, I will not be using the
'default' calculated configuration that it suggests but I noticed the
shmall = shmmax / page_size (4096).
I'll benchmark with both calculations but I would really appreciate some
confirmation on this.
thanks
Michael
