Messages in this thread | | | Date | Fri, 23 Oct 2009 09:45:33 +0200 | From | Ingo Molnar <> | Subject | [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel build times |
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Steve,
i did an 64-bit allyesconfig build test (with debug_info disabled), with and without CONFIG_DYNAMIC_FTRACE set.
The build time results are:
-CONFIG_DYNAMIC_FTRACE: 266.30 +CONFIG_DYNAMIC_FTRACE: 296.07 (+11.2%)
So we get more than 10% build time overhead.
That's quite high - higher than what i remember having measured originally when the first iteration of the mcount code went in.
This extra overhead comes from the mcount post-processing script (scripts/recordmcount.pl) that runs objcopy as well and is written in Perl. I think this whole angle needs to be improved - 10% is way too high of a price to pay.
Ingo
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