<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 19 Apr 2017, at 16:28, Gianluca Cecchi <<a href="mailto:gianluca.cecchi@gmail.com" class="">gianluca.cecchi@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote">On Wed, Apr 19, 2017 at 3:44 PM, Martin Polednik <span dir="ltr" class=""><<a href="mailto:mpolednik@redhat.com" target="_blank" class="">mpolednik@redhat.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br class="">
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If you are using recent CentOS (or I guess Fedora), there isn't any<br class="">
extra setup required. Just create the custom property:<br class=""></blockquote><div class=""><br class=""></div><div class="">Both my engine and my hosts are CentOS 7.3 + updates</div></div></div></div></div></blockquote><div><br class=""></div>that’s good</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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On the host where engine is running:<br class="">
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$ engine-config -s "UserDefinedVMProperties=hugep<wbr class="">ages=^.*$"<br class="">
$ service ovirt-engine restart<br class="">
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and you should see 'hugepages' when editing a VM under custom properties.<br class=""></blockquote><div class=""><br class=""></div><div class="">So no vdsm hook at all to install?</div></div></div></div></div></blockquote><div><br class=""></div>today you still need the hook.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""><br class=""></div><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Set the number to (desired memory / 2048) and you're good to go. The<br class="">
VM will run with it's memory backed by hugepages. </blockquote><div class=""><br class=""></div><div class="">As in sysctl.conf? So that if I want 4Gb of Huge Pages I have to set 2048?</div></div></div></div></div></blockquote><div><br class=""></div>yes. there might be some </div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""><br class=""></div><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">If you need<br class="">
hugepages even inside the VM, do whatever you would do on a physical<br class="">
host.<br class="">
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mpolednik<div class="HOEnZb"><div class="h5"><br class=""></div></div></blockquote><div class=""><br class=""></div><div class="">yes, the main subject is to have Huge Pages inside the guest, so that Oracle RDBMS at startup detect them and use them</div></div></div></div></div></blockquote><div><br class=""></div>yes, so if you do that via sysctl.conf on real HW just do the same here, or modify kernel cmdline.</div><div><br class=""></div><div>Note that those are two separate things</div><div>the hook is making QEMU process use hugepages memory in the host - that improves performance of any VM</div><div>then how it looks in guest is no concern to oVirt, it’s guest-side hugepages. You can enable/set them regardless the previous step, which may be fine if you just want to expose the capability to some app - e.g. in testing that the guest-side Oracle can work with hugepages in the guest.</div><div>But you probably want both Oracle to see hugepages and also actually use them - then you need both reserve that on host for qemu process and then inside guest reserve that for oracle. I.e. you need to add a “buffer” on host side to accommodate the non-hugepages parts of the guest e.g. on 24GB host you can reserve 20GB hugepages for VMs to use, and then run a VM with 20GB memory, reserving 16GB hugepages inside the guest for oracle to use.</div><div><br class=""></div><div>Thanks,</div><div>michal</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""><br class=""></div><div class="">Gianluca </div></div></div></div>
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