lkml.org 
[lkml]   [2022]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v3 00/54] lib/bitmap: optimize bitmap_weight() usage
Date
On 1/23/22 20:38, Yury Norov wrote:
> In many cases people use bitmap_weight()-based functions to compare
> the result against a number of expression:
>
> if (cpumask_weight(mask) > 1)
> do_something();
>
> This may take considerable amount of time on many-cpus machines because
> cpumask_weight() will traverse every word of underlying cpumask
> unconditionally.
>
> We can significantly improve on it for many real cases if stop traversing
> the mask as soon as we count cpus to any number greater than 1:
>
> if (cpumask_weight_gt(mask, 1))
> do_something();

I guess I am part of the recipient list because I did the original
suggestion of adding the single_bit_set()?

If this is the case - well, I do like this series. Overall it looks good
to me - but I for sure did not go through all the changes in detail ;)
If there is some other reason to loop me in (Eg, if someone expects me
to take a more specific look on something) - please give me a nudge.

Best Regards
-- Matti Vaittinen


--
The Linux Kernel guy at ROHM Semiconductors

Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~ this year is the year of a signature writers block ~~
\
 
 \ /
  Last update: 2022-01-26 08:30    [W:0.226 / U:2.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site