Page MenuHomeFreeBSD

me_freebsd_mathieu.digital (Mathieu Chouquet-Stringer)
User

Projects

User does not belong to any projects.

User Details

User Since
Mar 31 2021, 11:08 PM (5 w, 1 d)

Recent Activity

Tue, Apr 20

me_freebsd_mathieu.digital added a comment to D29733: kvmclock driver with vDSO support.

Thanks in advance to anyone willing to review this and/or provide any feedback after taking it for a spin!

Tue, Apr 20, 10:06 PM

Sat, Apr 17

me_freebsd_mathieu.digital added a comment to D29733: kvmclock driver with vDSO support.

Thanks a lot for helping to test-drive this!

Sat, Apr 17, 2:33 PM

Fri, Apr 16

me_freebsd_mathieu.digital added a comment to D29733: kvmclock driver with vDSO support.

I applied the patch to my source tree and while compiling and using the kernel works perfectly, compiling libc failed:

Fri, Apr 16, 1:02 PM

Thu, Apr 8

me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

As I mentioned previously, my employer has contracted work to bring this driver to a full implementation. An initial draft is under review internally and a Phabricator review is queued up once we give the green light. That is why I suggested holding off on this version of the patch.

Thu, Apr 8, 6:33 PM

Wed, Apr 7

me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

Oh fair enough, I'm uploading the newer version of the diff...

Wed, Apr 7, 11:03 PM
me_freebsd_mathieu.digital updated the diff for D29531: Add kvmclock timecounter support to FreeBSD.

Adding kvmclock to FreeBSD

Wed, Apr 7, 11:03 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

In addition to the copyright thing mentioned inline, a question: This is for FreeBSD VMs running under Linux Kernel-based Virtual Machine, correct?

Wed, Apr 7, 10:48 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

I think this is how optional features work, let me know if I got it completely wrong. And sadly when arc diff --update really messes up with the notes, not sure if I'm using it wrong...

Wed, Apr 7, 10:15 PM
me_freebsd_mathieu.digital updated the diff for D29531: Add kvmclock timecounter support to FreeBSD.
  • Make kvm_clock an optional feature
Wed, Apr 7, 10:13 PM
me_freebsd_mathieu.digital added inline comments to D29531: Add kvmclock timecounter support to FreeBSD.
Wed, Apr 7, 9:34 PM
me_freebsd_mathieu.digital added inline comments to D29531: Add kvmclock timecounter support to FreeBSD.
Wed, Apr 7, 9:32 PM
me_freebsd_mathieu.digital updated the diff for D29531: Add kvmclock timecounter support to FreeBSD.
  • Used designated initializers
  • Added a comment to explain what the magical | 1 means
  • Removed useless variable
Wed, Apr 7, 9:30 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

Here's what I get with doing random reads with fio on the device used by zfs (meaning I'm trying to see if the selected timecounter has an impact on the block device layer). Command used was:

fio --filename=/dev/vtbd0 --direct=1 --rw=randread --bs=4k --ioengine=posixaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1 --readonly
Wed, Apr 7, 5:52 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

As I mentioned previously, the other thing to consider when using kvmclock in the current patch is the need for a system call for clock_gettime(), gettimeofday(), etc.

When using the TSC, one gets the advantage of timehands structures being updated in the shared memory page, that libc then can use without the need for a system call.
This is also true for HPET (although the HPET is usually a terrible clock source for VM guests) and the reference TSC in Hyper-V deployments.

Wed, Apr 7, 5:29 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

@me_freebsd_mathieu.digital, what a CPU model was used for testing?

Wed, Apr 7, 4:54 PM

Apr 6 2021

me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

That work is actively in progress.

Therefore, we may want to hold off trying to commit something right now.

Apr 6 2021, 11:25 PM
me_freebsd_mathieu.digital updated the diff for D29531: Add kvmclock timecounter support to FreeBSD.
  • Removed headers as requested
Apr 6 2021, 10:50 PM
me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.
In D29531#663896, @imp wrote:

A number of people are reporting problems with zfs scrub w/o this fix that they say is corrected by this, so there's some desirer to have it in the tree. Do you know if these setups are common? Or do you have a notion of why these results have been reported in light of this instability?

Apr 6 2021, 8:26 PM

Apr 1 2021

me_freebsd_mathieu.digital added a comment to D29531: Add kvmclock timecounter support to FreeBSD.

Sounds good, I will wait to hear from him before updating the diff.

Apr 1 2021, 3:55 PM
me_freebsd_mathieu.digital retitled D29531: Add kvmclock timecounter support to FreeBSD from Add kvmclock support to FreeBSD to Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:23 PM
me_freebsd_mathieu.digital updated me_freebsd_mathieu.digital.
Apr 1 2021, 12:22 PM
me_freebsd_mathieu.digital updated me_freebsd_mathieu.digital.
Apr 1 2021, 12:21 PM
me_freebsd_mathieu.digital updated the summary of D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:19 PM
me_freebsd_mathieu.digital updated the test plan for D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:18 PM
me_freebsd_mathieu.digital updated the summary of D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:17 PM
me_freebsd_mathieu.digital updated the summary of D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:14 PM
me_freebsd_mathieu.digital updated the summary of D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 12:13 PM
me_freebsd_mathieu.digital retitled D29531: Add kvmclock timecounter support to FreeBSD from Added kvmclock to Add kvmclock support to FreeBSD.
Apr 1 2021, 12:12 PM
me_freebsd_mathieu.digital requested review of D29531: Add kvmclock timecounter support to FreeBSD.
Apr 1 2021, 11:43 AM