Messages in this thread | | | Subject | Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write() | From | Steven Rostedt <> | Date | Tue, 20 Sep 2011 11:19:47 -0400 |
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On Tue, 2011-09-20 at 09:57 -0500, Christoph Lameter wrote:
> this_cpu_xx functions are made for those locations that have > preemption enabled. If you can use those function (classic case is a > per cpu counter increment in the network subsystem) then you can avoid > preempt disable/enable or get_cpu/put_cpu.
If the variables are used for a very short time, then the latencies introduced by a simple:
var = get_cpu_var(my_var); if (var) do_something_quick(); put_cpu_var(my_var);
Otherwise if that do_something_quick(); migrates, it may be doing something it shouldn't be doing!
-- Steve
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