Host: Debian Linux 8, VBox RC3, 48 CPUs (24 Core+HT), Intel Xeon Haswell. (Intel(R) Xeon(R) CPU E5-2670 v3 @ 2.30GHz) + 288 GB of RAM.
Guest: Debian Linux 6, 32 CPUs
Good news ! I could put a hands on one of the servers around. Big-Iron. Many-Cores. Lot'-t-a-RAM.
The guest stucks right on setup. That is, it can't seem to sync across threads of different CPUs.
Guest has 32 cores, more than physical CPU cores.
Reducing guest SMP to 24 CPUs (to match host's physical cores) solved the issue. Still, I believe it should not stuck -or- ban all use of hyper-threading for VirtualBox engine. That is, VirtualBox should refuse to start, if it is hard to fix hyper-threading.
VMM: Hyper-threading doesn't work on big iron
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Technologov
- Volunteer
- Posts: 3342
- Joined: 10. May 2007, 16:59
- Location: Israel
VMM: Hyper-threading doesn't work on big iron
- Attachments
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- Debian 6 24 CPU-2015-07-05-10-58-43.zip
- (works fine w/ 24 CPUs, despite lots of warnings in log)
- (25.63 KiB) Downloaded 20 times
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- Debian 6 48 CPU-2015-07-05-10-33-44.zip
- (problematic w/ 32 CPUs)
- (40.05 KiB) Downloaded 20 times
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frank
- Oracle Corporation
- Posts: 3362
- Joined: 7. Jun 2007, 09:11
- Primary OS: Debian Sid
- VBox Version: PUEL
- Guest OSses: Linux, Windows
- Location: Dresden, Germany
- Contact:
Re: VMM: Hyper-threading doesn't work on big iron
There is nothing to "fix". VirtualBox just starts one execution thread per VCPU. A hyper thread is not a fully-fledged CPU core. And it depends on the guest if it's possible to boot a guest with more VCPUs than physical cores on the host. If the guest keeps all VCPUs busy at the same time then this will not work.
And this report does not belong to the Beta forum!
And this report does not belong to the Beta forum!