Re: [RFC PATCH v5 09/10] thermal: add trace events to the power allocator governor
From: Steven Rostedt
Date: Thu Jul 10 2014 - 14:04:00 EST
On Thu, 10 Jul 2014 17:20:14 +0100
"Javi Merino" <javi.merino@xxxxxxx> wrote:
> > How many CPUs are you saving load_cpu on? A trace event can't be bigger
> > than a page. And the data is actually a little less than that with the
> > required headers.
> The biggest system I've tested it on is an 8 cpu system (with
> NR_CPUS==8). So yes, small and we haven't seen any issues.
> Are you saying that we are siphoning too much data through ftrace? He
> find it really valuable to collect information during run and process
> it afterwards but I can see how this may not be feasible for systems
> with thousands of cpus.
Only too much for a single event. Perhaps have the tracepoint post per
CPU? Then you wouldn't need that array.
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