Hi Kirill, On Wed, 8 Aug 2018 12:59:40 +0300 Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> wrote: > > On 08.08.2018 04:08, Stephen Rothwell wrote: > > > > So what sort of overheads (in terms of code size and performance) are > > we adding by having SRCU enabled where it used not to be? > > SRCU is unconditionally enabled for x86, so I had to use another arch (sparc64) > to check the size difference. The config, I used to compile, is attached, SRCU > was enabled via: > > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index 2d58c26bff9a..6e9116e356d4 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -15,6 +15,7 @@ config SPARC > select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI > select ARCH_MIGHT_HAVE_PC_SERIO > select OF > + select SRCU > select OF_PROMTREE > select HAVE_IDE > select HAVE_OPROFILE > > $ size image.srcu.disabled > text data bss dec hex filename > 5117546 8030506 1968104 15116156 e6a77c image.srcu.disabled > > $ size image.srcu.enabled > text data bss dec hex filename > 5126175 8064346 1968104 15158625 e74d61 image.srcu.enabled > > The difference is: 15158625-15116156 = 42469 ~41Kb Thanks for that. > I have not ideas about performance overhead measurements. If you have ideas, > where they may occur, please say. At the first sight, there should not be > a problem, since SRCU is enabled in x86 by default. I have no idea, just asking questions that might be relevant for platforms where SRCU is normally disabled. -- Cheers, Stephen Rothwell
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