On Mon, Dec 11, 2006 at 03:15:44PM -0800, dean gaudet wrote:
> rdtscp gets you 2 of the 5 values you need to compute the time. anything
> can happen between when you do the rdtscp and do the other 3 reads: the
> computation is (((tsc-A)*B)>>N)+C where N is a constant, and A, B, C are
>
On Mon, 11 Dec 2006, Andrea Arcangeli wrote:
> On Mon, Dec 11, 2006 at 01:17:25PM -0800, dean gaudet wrote:
> > rdtscp doesn't solve anything extra [..]
> > [..] lsl-based vgetcpu is relatively slow
>
> Well, if you accept to run slow there's nothing to solve in the first
> place indeed.
>
> If
On Mon, Dec 11, 2006 at 01:17:25PM -0800, dean gaudet wrote:
> rdtscp doesn't solve anything extra [..]
> [..] lsl-based vgetcpu is relatively slow
Well, if you accept to run slow there's nothing to solve in the first
place indeed.
If nothing else rdtscp should avoid the mess of restarting a
On Mon, 11 Dec 2006, Andrea Arcangeli wrote:
> As far as I can see, many changes happened but nobody has yet added
> the rdtscp support to x86-64. rdtscp finally solves the problem and it
> obsoletes hpet for timekeeping and it allows a fully userland
> gettimeofday running at maximum speed in
On Mon, 11 Dec 2006, Andrea Arcangeli wrote:
As far as I can see, many changes happened but nobody has yet added
the rdtscp support to x86-64. rdtscp finally solves the problem and it
obsoletes hpet for timekeeping and it allows a fully userland
gettimeofday running at maximum speed in
On Mon, Dec 11, 2006 at 01:17:25PM -0800, dean gaudet wrote:
rdtscp doesn't solve anything extra [..]
[..] lsl-based vgetcpu is relatively slow
Well, if you accept to run slow there's nothing to solve in the first
place indeed.
If nothing else rdtscp should avoid the mess of restarting a
On Mon, 11 Dec 2006, Andrea Arcangeli wrote:
On Mon, Dec 11, 2006 at 01:17:25PM -0800, dean gaudet wrote:
rdtscp doesn't solve anything extra [..]
[..] lsl-based vgetcpu is relatively slow
Well, if you accept to run slow there's nothing to solve in the first
place indeed.
If nothing
On Mon, Dec 11, 2006 at 03:15:44PM -0800, dean gaudet wrote:
rdtscp gets you 2 of the 5 values you need to compute the time. anything
can happen between when you do the rdtscp and do the other 3 reads: the
computation is (((tsc-A)*B)N)+C where N is a constant, and A, B, C are
per-cpu
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