Re: [ovirt-users] Question about Huge Pages
On 18 Apr 2017, at 18:03, Gianluca Cecchi
<gianluca.cecchi(a)gmail.com> wrote:
Hello,
I'm testing virtualization of some Oracle servers.
I have 4.1.1 with CentOS 7.3 servers as hypervisors.
Typically on physical Oracle servers I configure huge pages for Oracle memory areas.
In particular I disable Transparent Huge Pages, because they are known to be in conflict
with Oracle performances, both in RAC and in standalone configurations.
In RHEL systems I configure "transparent_hugepage=never" boot parameter, while
in Oracle Linux OS uek kernels it is already disabled by default.
I notice that in CentOS 7.3, by default, transparent huge pages are configured:
[root@ov300 ~]# cat /proc/meminfo | grep -i huge
AnonHugePages: 17006592 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
[root@ov300 ~]#
I'm going to configure a VM with 64Gb of ram and with an Oracle RDBMS that would have
16Gb of SGA.
I suspect that I could have problems if I dont' change configuration at hypervisor
level...
What do you think about this subject?
Is there any drawback if I manually configure the hypervisors to boot with the
"transparent_hugepage=never" boot parameter?
Why not reserving regular hugepages for VMs on boot? then you can use
it with vdsm hook for that Oracle VM. It improves VM performance in
general, the only drawback is less flexibility since that memory can't
be used by others unless they specifically ask for hugepages.
Also, I suppose you disable KSM, and I'm not sure about ballooning,
unless you need it I'd disable it too.
The hook is being improved right now in master, but it should be
usable in stable too.
Thanks,
michal
Thanks in advance,
Gianluca
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users