| Message ID | 20210225135700.1381396-3-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arch: enable GENERIC_FIND_FIRST_BIT for MIPS and ARM64 | expand |
Hi, Yury, On Thu, Feb 25, 2021 at 9:59 PM Yury Norov <yury.norov@gmail.com> wrote: > > From: Alexander Lobakin <alobakin@pm.me> > > MIPS doesn't have architecture-optimized bitsearching functions, > like find_{first,next}_bit() etc. Emm, I think MIPS can use clo/clz to optimize bitsearching functions. Huacai > It's absolutely harmless to enable GENERIC_FIND_FIRST_BIT as this > functionality is not new at all and well-tested. It provides more > optimized code and saves some .text memory (32 R2): > > add/remove: 4/1 grow/shrink: 1/53 up/down: 216/-372 (-156) > > Users of for_each_set_bit() like hotpath gic_handle_shared_int() > will also benefit from this. > > Suggested-by: Yury Norov <yury.norov@gmail.com> > Signed-off-by: Alexander Lobakin <alobakin@pm.me> > Signed-off-by: Yury Norov <yury.norov@gmail.com> > --- > arch/mips/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index d89efba3d8a4..164bdd715d4b 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -26,6 +26,7 @@ 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 > -- > 2.25.1 >
On Fri, Feb 26, 2021 at 09:22:18AM +0800, Huacai Chen wrote: > Hi, Yury, > > On Thu, Feb 25, 2021 at 9:59 PM Yury Norov <yury.norov@gmail.com> wrote: > > > > From: Alexander Lobakin <alobakin@pm.me> > > > > MIPS doesn't have architecture-optimized bitsearching functions, > > like find_{first,next}_bit() etc. > Emm, I think MIPS can use clo/clz to optimize bitsearching functions. find_{first,next}_bit() is about manipulating the bitmaps bigger that a single word, and some arches (arm) implement their own find_bit() functions. find_bit() is not a replacement of __ffs() and ffz(). > Huacai > > > It's absolutely harmless to enable GENERIC_FIND_FIRST_BIT as this > > functionality is not new at all and well-tested. It provides more > > optimized code and saves some .text memory (32 R2): > > > > add/remove: 4/1 grow/shrink: 1/53 up/down: 216/-372 (-156) > > > > Users of for_each_set_bit() like hotpath gic_handle_shared_int() > > will also benefit from this. > > > > Suggested-by: Yury Norov <yury.norov@gmail.com> > > Signed-off-by: Alexander Lobakin <alobakin@pm.me> > > Signed-off-by: Yury Norov <yury.norov@gmail.com> > > --- > > arch/mips/Kconfig | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > > index d89efba3d8a4..164bdd715d4b 100644 > > --- a/arch/mips/Kconfig > > +++ b/arch/mips/Kconfig > > @@ -26,6 +26,7 @@ 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 > > -- > > 2.25.1 > >
On Thu, Feb 25, 2021 at 05:57:00AM -0800, Yury Norov wrote: > From: Alexander Lobakin <alobakin@pm.me> > > MIPS doesn't have architecture-optimized bitsearching functions, > like find_{first,next}_bit() etc. > It's absolutely harmless to enable GENERIC_FIND_FIRST_BIT as this > functionality is not new at all and well-tested. It provides more > optimized code and saves some .text memory (32 R2): > > add/remove: 4/1 grow/shrink: 1/53 up/down: 216/-372 (-156) > > Users of for_each_set_bit() like hotpath gic_handle_shared_int() > will also benefit from this. > > Suggested-by: Yury Norov <yury.norov@gmail.com> > Signed-off-by: Alexander Lobakin <alobakin@pm.me> > Signed-off-by: Yury Norov <yury.norov@gmail.com> > --- > arch/mips/Kconfig | 1 + > 1 file changed, 1 insertion(+) applied to mips-next. Thomas.
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d89efba3d8a4..164bdd715d4b 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -26,6 +26,7 @@ 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