Re: perf-stat changes after "Use hrtimers for event multiplexing"

2014-01-07 Thread Stephane Eranian
On Tue, Jan 7, 2014 at 2:20 PM, Fengguang Wu wrote: > Hi Stephane, > > On Tue, Jan 07, 2014 at 10:52:50AM +0100, Stephane Eranian wrote: >> Hi, >> >> With the hrtitmer patch, you will get more regular multiplexing when >> you have idle cores during your benchmark. >> Without the patch, multiplexin

Re: perf-stat changes after "Use hrtimers for event multiplexing"

2014-01-07 Thread Fengguang Wu
Hi Stephane, On Tue, Jan 07, 2014 at 10:52:50AM +0100, Stephane Eranian wrote: > Hi, > > With the hrtitmer patch, you will get more regular multiplexing when > you have idle cores during your benchmark. > Without the patch, multiplexing was piggybacked on timer tick. The > timer tick does not occ

Re: perf-stat changes after "Use hrtimers for event multiplexing"

2014-01-07 Thread Stephane Eranian
Hi, With the hrtitmer patch, you will get more regular multiplexing when you have idle cores during your benchmark. Without the patch, multiplexing was piggybacked on timer tick. The timer tick does not occur when a core is idle when using a tickless kernel. Thus, the quality of the results with h

Re: perf-stat changes after "Use hrtimers for event multiplexing"

2014-01-04 Thread Fengguang Wu
On Sat, Jan 04, 2014 at 08:02:28PM +0100, Peter Zijlstra wrote: > On Thu, Jan 02, 2014 at 02:12:42PM +0800, fengguang...@intel.com wrote: > > Greetings, > > > > We noticed many perf-stat changes between commit 9e6302056f ("perf: Use > > hrtimers for event multiplexing") and its parent commit ab573

Re: perf-stat changes after "Use hrtimers for event multiplexing"

2014-01-04 Thread Peter Zijlstra
On Thu, Jan 02, 2014 at 02:12:42PM +0800, fengguang...@intel.com wrote: > Greetings, > > We noticed many perf-stat changes between commit 9e6302056f ("perf: Use > hrtimers for event multiplexing") and its parent commit ab573844e. > Are these expected changes? > > ab573844e3058ee 9e6302056f8029f4