Messages in this thread | | | Subject | Re: More weird latency trace output (was Re: 2.6.17-rt1) | From | Lee Revell <> | Date | Thu, 22 Jun 2006 21:24:52 -0400 |
| |
On Wed, 2006-06-21 at 22:51 -0400, Lee Revell wrote: > How can the latency tracer be reporting 1898us max latency while the > trace is of a 12us latency? This must be a bug, correct?
I've found the bug. The latency tracer uses get_cycles() for timestamping, which uses rdtsc, which is unusable for timing on dual core AMD64 machines due to the well known "unsynced TSCs" hardware bug.
Would a patch to convert the latency tracer to use gettimeofday() be acceptable?
Lee
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |