VirtualBox

Ticket #2270 (closed defect: fixed)

Opened 6 years ago

Last modified 5 years ago

Large page problems for RedHat 5 guest applications

Reported by: ChrisJenkins Owned by:
Priority: major Component: other
Version: VirtualBox 2.0.2 Keywords:
Cc: Guest type: Linux
Host type: Windows

Description

I am running VirtualBox 2.0.2 32-bit on Windows XP SP3 with an Intel Core2 Duo T7300 CPU. I installed RedHat Enterprise Linux (actually oracle Enterprise Linux which is a rebadged version) with kernel version 2.6.18-92.

Linux detects the HugePageSize as 4 Mb (as per cat /proc/meminfo) which is incorrect; it should be 2 Mb (this works correctly under VMware). Asa result, several pieces of software that use large pages do not work correctly.

Since the page size is detected properly when installed on real hardware and also within VMware on the same host it would seem this is due to some issue with VirtualBox. I have tried with both software and hardware virtualisation but it behaves thesame.

Change History

comment:1 Changed 6 years ago by sandervl73

  • Status changed from new to closed
  • Resolution set to invalid

Unless you turn on PAE for the guest, large pages will be 4 MB. So enabling this in the VM settings will 'fix' your problem.

Closing this defect. Please reopen if there are other issues related to large pages.

comment:2 Changed 6 years ago by ChrisJenkins

  • Status changed from closed to reopened
  • Resolution invalid deleted

Enabled PAE/NX in VM settings and booted VM but Linux still reports large page size as 4 Mb...

comment:3 Changed 6 years ago by sandervl73

You probably need to reinstall/rebuild the kernel. Afaik you can't simply switch between PAE and non-PAE on the fly with Linux.

comment:4 Changed 6 years ago by ChrisJenkins

As it turns out, the RHEL 5 / OEL 5 (and probably RHEL 4 as well) uniprocessor kernel does not include PAE support (the SMP kernel does). However, there is a PAE enabled uniprocessor kernel available in the distribution so I installed that and now I do indeed see huge pages as being 2 Mb in size. However, our application that uses huge pages still has major problems when running in VirtualBox which it does not have when running on real hardware or under VMware. We are still investigating this. I will open a separate ticket on this once we have more information. You can close this ticket. Thanks.

comment:5 Changed 6 years ago by sandervl73

  • Summary changed from Kernel detects incorrect large page size for RedHat 5 on Windows host to Large page problems for RedHat 5 on Windows host

If you can come up with a testcase that shows the problem, then I'd be happy to take a look.

I've renamed the defect, so you can post further findings later.

comment:6 Changed 6 years ago by sandervl73

  • Summary changed from Large page problems for RedHat 5 on Windows host to Large page problems for RedHat 5 guest applications

comment:7 Changed 5 years ago by frank

  • Status changed from reopened to closed
  • Resolution set to fixed

Please reopen if this problem persists with the latest release 2.2.0.

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