Messages in this thread | | | Date | Thu, 8 Dec 2016 08:56:48 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86/tsc: RFC: re-synchronize TSCs to boot cpu TSC |
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On Thu, 8 Dec 2016, sroland@vmware.com wrote:
> From: Roland Scheidegger <rscheidegger_lists@hispeed.ch> > > Some bios (Dell T5810 here) mess up the perfectly synced TSCs on boot > and resume (probably trying to set some continuous time, but writing > TSC directly instead of TSC_ADJUST which can only result in failure). > This will cause the kernel to reject the tsc as clocksource due to > the detected time warp. > Try to fix this up by syncing the TSCs of non-boot cpus to the boot > cpu, both on boot and resume. > I've got some use case here which relies on really fast time > measurements, without TSCs things run noticeably slower (ok the > measurements probably are excessive) (and the timing information is > probably useless too without TSCs). > (This is quite a big hack, I have no idea what happens with > multi-socket systems for instance, but it near certainly won't be > right. I really don't know what I'm doing here, it is not a proper > patch but a working (for me) proof-of-concept hack I've been using > since a while although actually only with kernel 4.4 - I suppose > some proper quirk would be needed. I guess there's also some chance > SMM in general could do further damage to TSCs sometimes making this > hack fail.)
Can you please try
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/timers
which contains a solution to this problem.
Thanks,
tglx
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