Hi.
On 2020/06/15 7:08, Andrew Doran wrote:
On Thu, Jun 11, 2020 at 04:50:40AM +, Taylor R Campbell wrote:
What's trickier is synchronizing per-CPU timecounters so that they all
give a reasonably consistent view of absolute wall clock time -- and
so it's not just one CPU that leads while t
On Thu, Jun 11, 2020 at 04:50:40AM +, Taylor R Campbell wrote:
> What's trickier is synchronizing per-CPU timecounters so that they all
> give a reasonably consistent view of absolute wall clock time -- and
> so it's not just one CPU that leads while the others play catchup
> every time they t
> Date: Wed, 10 Jun 2020 23:11:32 +
> From: Andrew Doran
>
> On Tue, Jun 09, 2020 at 05:16:27PM +, Taylor R Campbell wrote:
>
> > At the same time, I wonder whether we should _also_:
> >
> > 1. Modify the tsc timecounter so that it uses a global atomic to
> >ensure that there is a g
Hi.
On 2020/06/10 4:37, Joerg Sonnenberger wrote:
> On Tue, Jun 09, 2020 at 05:16:27PM +, Taylor R Campbell wrote:
>> It's great to see improvements to our calibration of the TSC (and I
>> tend to agree that cpu_counter should be serializing, so that, e.g.,
>> cpu_counter(); ...; cpu_counter()
On Tue, Jun 09, 2020 at 05:16:27PM +, Taylor R Campbell wrote:
> It's great to see improvements to our calibration of the TSC (and I
> tend to agree that cpu_counter should be serializing, so that, e.g.,
> cpu_counter(); ...; cpu_counter() reliably measures time taken in the
> ellipsis).
>
>
On Tue, Jun 09, 2020 at 05:16:27PM +, Taylor R Campbell wrote:
> It's great to see improvements to our calibration of the TSC (and I
> tend to agree that cpu_counter should be serializing, so that, e.g.,
> cpu_counter(); ...; cpu_counter() reliably measures time taken in the
> ellipsis).
I'm p
It's great to see improvements to our calibration of the TSC (and I
tend to agree that cpu_counter should be serializing, so that, e.g.,
cpu_counter(); ...; cpu_counter() reliably measures time taken in the
ellipsis).
At the same time, I wonder whether we should _also_:
1. Modify the tsc timecoun
Hi, all.
I wrote a code to improve x86's TSC.x86/tsc.c rev. 1.67 reduced cache
problem, but it still has room. I measured the effect of lfence, mfence,
cpuid and rdtscp. The impact to TSC skew and/or drift is:
AMD: mfence > rdtscp > cpuid > lfence-serialize > lfence = nomodify
