On Wed, Feb 17, 2021 at 08:05:06PM -0800, Yury Norov wrote: > This series introduces fast paths for find_bit() routines. It is > beneficial for typical systems, but those who limited in I-cache > may be concerned about increasing the .text size of the Image. > > To address this concern, one can disable FAST_PATH option in the config > and some save memory. > > The effect of this option on my arm64 next-20210217 build is: (Maybe bloat-o-meter will give better view on this, i.e. more human-readable) > Before: > Sections: > Idx Name Size VMA LMA File off Algn > 0 .head.text 00010000 ffff800010000000 ffff800010000000 00010000 2**16 > CONTENTS, ALLOC, LOAD, READONLY, CODE > 1 .text 0115e3a8 ffff800010010000 ffff800010010000 00020000 2**16 > CONTENTS, ALLOC, LOAD, READONLY, CODE > 2 .got.plt 00000018 ffff80001116e3a8 ffff80001116e3a8 0117e3a8 2**3 > CONTENTS, ALLOC, LOAD, DATA > 3 .rodata 007a72ca ffff800011170000 ffff800011170000 01180000 2**12 > CONTENTS, ALLOC, LOAD, DATA > ... > > After: > Sections: > Idx Name Size VMA LMA File off Algn > 0 .head.text 00010000 ffff800010000000 ffff800010000000 00010000 2**16 > CONTENTS, ALLOC, LOAD, READONLY, CODE > 1 .text 011623a8 ffff800010010000 ffff800010010000 00020000 2**16 > CONTENTS, ALLOC, LOAD, READONLY, CODE > 2 .got.plt 00000018 ffff8000111723a8 ffff8000111723a8 011823a8 2**3 > CONTENTS, ALLOC, LOAD, DATA > 3 .rodata 007a772a ffff800011180000 ffff800011180000 01190000 2**12 > CONTENTS, ALLOC, LOAD, DATA > ... > > Notice that this is the cumulive effect on already existing fast paths > controlled by SMALL_CONST() together with ones added by this series. ... > +config FAST_PATH I think the name is to broad for this cases, perhaps BITS_FAST_PATH? or BITMAP? > + bool "Enable fast path code generation" > + default y > + help > + This option enables fast path optimization with the cost of increasing > + the text section. -- With Best Regards, Andy Shevchenko
