Messages in this thread | | | Date | Sat, 7 Jul 2007 19:59:39 +0200 | From | Adrian Bunk <> | Subject | Re: [patch 10/10] Scheduler profiling - Use immediate values |
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On Sat, Jul 07, 2007 at 07:20:12PM +0200, Willy Tarreau wrote: > On Sat, Jul 07, 2007 at 07:01:57PM +0200, Adrian Bunk wrote: > > On Sat, Jul 07, 2007 at 11:45:20AM -0400, Frank Ch. Eigler wrote: >... > > You always have to decide between some debug code and some small bit of > > performance. There's a reason why options to disable things like BUG() > > or printk() are in the kernel config menus hidden behind CONFIG_EMBEDDED > > although they obviously have some performance impact. > > It is not for the CPU performance they can be disabled, but for the code > size which is a real problem on embedded system. While you often have > mem/cpu_mhz ratios around 1GB/1GHz on servers and desktops, you more often > have ratios like 16MB/500MHz which is 1:32 of the former. That's why you > optimize for size at the expense of speed on such systems.
The latter is not true for my two examples.
CONFIG_PRINTK=n, CONFIG_BUG=n will obviously make the kernel both smaller and faster. [1]
> Regards, > Willy
cu Adrian
[1] faster due to less code to execute and positive cache effects due to the smaller code [2] [2] whether the "faster" is big enough that it is in any way measurable is a different question
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