On Mon, May 10, 2021 at 04:34:21PM -0700, Yury Norov wrote: > In the 5.12 cycle we enabled the GENERIC_FIND_FIRST_BIT config option > for ARM64 and MIPS. It increased performance and shrunk .text size; and > so far I didn't receive any negative feedback on the change. > > https://lore.kernel.org/linux-arch/20210225135700.1381396-1-yury.norov@xxxxxxxxx/ > > I think it's time to make all architectures use find_{first,last}_bit() > unconditionally and remove the corresponding config option. > > This patch doesn't introduce functional changes for arc, arm64, mips, > s390 and x86 because they already enable GENERIC_FIND_FIRST_BIT. There > will be no changes for arm because it implements find_{first,last}_bit > in arch code. For other architectures I expect improvement both in > performance and .text size. Subject like s/all:/arch:/. > It would be great if people with an access to real hardware would share > the output of bloat-o-meter and lib/find_bit_benchmark. This is rather comment (should be below cutter '---' line). Anyway, seems good to my by the code: Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx> > --- > arch/arc/Kconfig | 1 - > arch/arm64/Kconfig | 1 - > arch/mips/Kconfig | 1 - > arch/s390/Kconfig | 1 - > arch/x86/Kconfig | 1 - > arch/x86/um/Kconfig | 1 - > include/asm-generic/bitops/find.h | 12 ------------ > lib/Kconfig | 3 --- > 8 files changed, 21 deletions(-) > > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > index bc8d6aecfbbd..9c991ba50db3 100644 > --- a/arch/arc/Kconfig > +++ b/arch/arc/Kconfig > @@ -19,7 +19,6 @@ config ARC > select COMMON_CLK > select DMA_DIRECT_REMAP > select GENERIC_ATOMIC64 if !ISA_ARCV2 || !(ARC_HAS_LL64 && ARC_HAS_LLSC) > - select GENERIC_FIND_FIRST_BIT > # for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP > select GENERIC_IRQ_SHOW > select GENERIC_PCI_IOMAP > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index e09a9591af45..9d5b36f7d981 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -108,7 +108,6 @@ config ARM64 > select GENERIC_CPU_AUTOPROBE > select GENERIC_CPU_VULNERABILITIES > select GENERIC_EARLY_IOREMAP > - select GENERIC_FIND_FIRST_BIT > select GENERIC_IDLE_POLL_SETUP > select GENERIC_IRQ_IPI > select GENERIC_IRQ_PROBE > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index b72458215d20..3ddae7918386 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -27,7 +27,6 @@ config MIPS > select GENERIC_ATOMIC64 if !64BIT > select GENERIC_CMOS_UPDATE > select GENERIC_CPU_AUTOPROBE > - select GENERIC_FIND_FIRST_BIT > select GENERIC_GETTIMEOFDAY > select GENERIC_IOMAP > select GENERIC_IRQ_PROBE > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index c1ff874e6c2e..3a10ceb8a097 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -125,7 +125,6 @@ config S390 > select GENERIC_CPU_AUTOPROBE > select GENERIC_CPU_VULNERABILITIES > select GENERIC_ENTRY > - select GENERIC_FIND_FIRST_BIT > select GENERIC_GETTIMEOFDAY > select GENERIC_PTDUMP > select GENERIC_SMP_IDLE_THREAD > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index b83364a15d34..6a7d8305365e 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -123,7 +123,6 @@ config X86 > select GENERIC_CPU_VULNERABILITIES > select GENERIC_EARLY_IOREMAP > select GENERIC_ENTRY > - select GENERIC_FIND_FIRST_BIT > select GENERIC_IOMAP > select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP > select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC > diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig > index 95d26a69088b..40d6a06e41c8 100644 > --- a/arch/x86/um/Kconfig > +++ b/arch/x86/um/Kconfig > @@ -8,7 +8,6 @@ endmenu > > config UML_X86 > def_bool y > - select GENERIC_FIND_FIRST_BIT > > config 64BIT > bool "64-bit kernel" if "$(SUBARCH)" = "x86" > diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h > index 0d132ee2a291..8a7b70c79e15 100644 > --- a/include/asm-generic/bitops/find.h > +++ b/include/asm-generic/bitops/find.h > @@ -95,8 +95,6 @@ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, > } > #endif > > -#ifdef CONFIG_GENERIC_FIND_FIRST_BIT > - > /** > * find_first_bit - find the first set bit in a memory region > * @addr: The address to start the search at > @@ -136,16 +134,6 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) > > return _find_first_zero_bit(addr, size); > } > -#else /* CONFIG_GENERIC_FIND_FIRST_BIT */ > - > -#ifndef find_first_bit > -#define find_first_bit(addr, size) find_next_bit((addr), (size), 0) > -#endif > -#ifndef find_first_zero_bit > -#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0) > -#endif > - > -#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ > > #ifndef find_last_bit > /** > diff --git a/lib/Kconfig b/lib/Kconfig > index a38cc61256f1..8346b3181214 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -59,9 +59,6 @@ config GENERIC_STRNLEN_USER > config GENERIC_NET_UTILS > bool > > -config GENERIC_FIND_FIRST_BIT > - bool > - > source "lib/math/Kconfig" > > config NO_GENERIC_PCI_IOPORT_MAP > -- > 2.25.1 > -- With Best Regards, Andy Shevchenko
