Does anyone try kib's Sandy Bridge PCID patch (pcid.2.patch)?

Kostik Belousov kostikbel at
Mon Jan 30 06:36:13 UTC 2012

On Mon, Jan 30, 2012 at 10:15:51AM +0800, Paul Ambrose wrote:
> I have two boxes, one is  AMD Athlon 610e 2.4G with FreeBSD-current
> patched with pcid.2.patch? It works well without other issue and it
> seem the pcid patch
> does not affect other part of the kernel. The other one is Sandy
Athlons do not have PCID and probably will never implement it. They use
other tricks to get similar optimizations, transparently to the OS.

> Bridge i5-2300 with FreeBSD 9 release patched with pcid.1.patch( the
> pcid.2.patch seems
> dependent on AVX and XSAVE stuffs which is available on -current). But
> it hangs up just in a few minutes. I doubt the nvidia-driver which is
> not recompiled with
> patched kernel is the root, I will check this out  later, but does
> anyone meet similar problem?
There are two many variations compared to the config I did tested.
I do not see anything obvious in the changes between HEAD and stable/9
which could be blamed. Nvidia driver might be bigger suspect, but again,
I am not aware of anything wrong with it.

> I have two question about the pcid.2.patch

Item 2 is clean, I fixed it.

For the item 1, I was only able to decipher the proposal to optimize
the global shootdown handler to restore the %cr3 with bit 64 set to not
invalidate current PCID. Is there some more changes ?

Thank you for looking at the patch.
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