Messages in this thread | | | Subject | Re: Q: perf log mode? | From | Peter Zijlstra <> | Date | Wed, 12 Jan 2011 15:53:41 +0100 |
| |
On Wed, 2011-01-12 at 15:42 +0100, Frederic Weisbecker wrote: > On Wed, Jan 12, 2011 at 03:08:08PM +0100, Peter Zijlstra wrote: > > On Wed, 2011-01-12 at 17:06 +0300, Kirill Smelkov wrote: > > > I'm trying to use perf together with e.g. kprobes as a tool to show what > > > is happening with my system in "live-log" mode. The problem is, for > > > seldom events, actual info output is largely delayed because perf reads > > > sample data in whole pages. Could something be done with it or am I'm > > > missing something? Here is detailed description: > > > > perf_event_attr = { > > .watermark = 0, > > .wakeup_events = 1, > > }; > > > Which is perhaps something we want as a default when perf record -c 1 > and the output is the pipe mode.
No, definitely not, esp for -c1 you want large buffers because the event can come at very high freq.
Nor does pipe mode have anything to do with it, the whole script set-up plain stinks and should not be using pipe mode, pipe mode should only be used to pipe data over the network and other remote profiling like things.
| |