lkml.org 
[lkml]   [2020]   [Jan]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/3] lib/find_bit.c: uninline helper _find_next_bit()
On Fri, Jan 03, 2020 at 04:08:43PM -0800, Yury Norov wrote:
> On Fri, Jan 03, 2020 at 01:46:07PM -0800, Joe Perches wrote:
> > On Fri, 2020-01-03 at 12:28 -0800, Yury Norov wrote:
> > > It saves 25% of .text for arm64, and more for BE architectures.
> >
> > This seems a rather misleading code size reduction description.
> >
> > Please detail the specific code sizes using "size lib/find_bit.o"
> > before and after this change.
>
> Before:
> $ size lib/find_bit.o
> text data bss dec hex filename
> 1012 56 0 1068 42c lib/find_bit.o
>
> After:
> $ size lib/find_bit.o
> text data bss dec hex filename
> 776 56 0 832 340 lib/find_bit.o
>
> > Also, _find_next_bit is used 3 times, perhaps any code size
> > increase is appropriate given likely reduced run time.
>
> Second patch of the series switches find_next_zero_bit_le()
> and find_next_bit_le() to _find_next_bit(), so totally 5.
>
> Yury

> > perhaps any code size
> > increase is appropriate given likely reduced run time.

I have a benchmark for the find_bit functions upstream, however, it cannot
measure the overall performance degradation related to increased probability
of cache eviction.

When I originally wrote _find_next_bit() in 2014, it was simpler and had 2
users. Now there are 5 of them, and I think it's good time to stop inlining
_find_next_bit().

Yury

\
 
 \ /
  Last update: 2020-01-04 02:07    [W:0.039 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site