Messages in this thread | | | Date | Mon, 23 Dec 2013 09:44:25 -0500 | From | David Ahern <> | Subject | Re: [PATCH] Perf: Correct Assumptions about Sample Timestamps in Passes |
| |
On 12/23/13, 8:10 AM, Frederic Weisbecker wrote: > On Fri, Dec 20, 2013 at 10:09:53AM -0700, David Ahern wrote: >> On 12/20/13, 5:27 AM, Joseph Schuchart wrote: >>> I know this comes late, but: As far as I can see, your change does not >>> preserve the logic of the code I suggested. The idea was to first gather >>> all the maximum timestamps of all cpus (that is, the last timestamp seen >>> on each cpu) and then determine the minimum of these maxima. These are >>> two distinct steps that I think cannot be combined in one update. Your >> >> A number of people have reported similar problems -- timestamps >> below last flush time. This approach would solve that problem for >> data processed from files, so it would be a good improvement. > > Could it be near what you're looking for? > > https://lkml.org/lkml/2012/2/18/53 >
Forgot about that patch. It is similar to what Joseph wants for analyzing a file.
I was carrying that patch while working on perf-kvm-stat-live last Fall. It does not solve the problem for live commands, so ended up dropping it and going with local (to the command) hacks. I still think for live commands getting a perf_clock timestamp at the start of a round and using that as the flush time will work best.
David
| |