Re: [PATCH] Implement timekeeping for rumprun/hw (x86)

  • From: Martin Lucina <martin@xxxxxxxxxx>
  • To: rumpkernel-users@xxxxxxxxxxxxx
  • Date: Mon, 6 Jul 2015 13:47:03 +0200

On Monday, 06.07.2015 at 11:23, Antti Kantee wrote:

On 06/07/15 10:50, Martin Lucina wrote:
On Monday, 06.07.2015 at 10:35, Antti Kantee wrote:
While that may be a fix, how can that even in theory be a fix for
the guest clock running at 2/5 speed compared to the real world??

The problem I was trying to fix was sleeps being
way too long on x86-64 (as reported by the test program).

The problem I reported: "The clock seems to run at about 2/5 speed
under no-kvm QEMU (i.e. sleep 2 takes ~5 seconds). Is that
expected?" I assumed you were fixing the reported problem.

Ah, right. Well, I can't reproduce that here at all :-(

Tested with QEMU emulator version 2.1.2 (Debian 1:2.1+dfsg-12~bpo70+1).

I've been testing with QEMU in kvm and non-kvm mode, tried the command line
manually, ... What is interesting is that my QEMU does not document a
"no-kvm" option but it does seem to accept it. I'll triple check again that
I'm not running in KVM mode all the time by accident, perhaps by booting
with the kvm module blacklisted or something.

What does "boot *directly* from GRUB" mean? Build an image with
grub and the test program and use "qemu img" instead of "qemu
-kernel bin", or what exactly? (not sure how that would be booting

I meant booting on bare metal directly. But since your problem appears to
be specific to "QEMU without kvm", that won't have anything to do with it,
except as a sanity check.

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