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* [PATCH] lib: micro-optimization for __bitmap_complement()
@ 2018-04-11 14:59 Yury Norov
2018-04-20 13:43 ` Yury Norov
0 siblings, 1 reply; 2+ messages in thread
From: Yury Norov @ 2018-04-11 14:59 UTC (permalink / raw)
To: Andrew Morton, Matthew Wilcox, Rasmus Villemoes, linux-kernel; +Cc: Yury Norov
Use BITS_TO_LONGS() macro to avoid calculation of reminder
(bits % BITS_PER_LONG) On ARM64 it saves 5 instruction for function -
16 before and 11 after.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
lib/bitmap.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/lib/bitmap.c b/lib/bitmap.c
index c82c61b66e16..7adc10074cff 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -62,12 +62,9 @@ EXPORT_SYMBOL(__bitmap_equal);
void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
{
- unsigned int k, lim = bits/BITS_PER_LONG;
+ unsigned int k, lim = BITS_TO_LONGS(bits);
for (k = 0; k < lim; ++k)
dst[k] = ~src[k];
-
- if (bits % BITS_PER_LONG)
- dst[k] = ~src[k];
}
EXPORT_SYMBOL(__bitmap_complement);
--
2.14.1
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH] lib: micro-optimization for __bitmap_complement()
2018-04-11 14:59 [PATCH] lib: micro-optimization for __bitmap_complement() Yury Norov
@ 2018-04-20 13:43 ` Yury Norov
0 siblings, 0 replies; 2+ messages in thread
From: Yury Norov @ 2018-04-20 13:43 UTC (permalink / raw)
To: Andrew Morton, Matthew Wilcox, Rasmus Villemoes, linux-kernel
Ping?
On Wed, Apr 11, 2018 at 05:59:14PM +0300, Yury Norov wrote:
> Use BITS_TO_LONGS() macro to avoid calculation of reminder
> (bits % BITS_PER_LONG) On ARM64 it saves 5 instruction for function -
> 16 before and 11 after.
>
> Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
> ---
> lib/bitmap.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index c82c61b66e16..7adc10074cff 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -62,12 +62,9 @@ EXPORT_SYMBOL(__bitmap_equal);
>
> void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
> {
> - unsigned int k, lim = bits/BITS_PER_LONG;
> + unsigned int k, lim = BITS_TO_LONGS(bits);
> for (k = 0; k < lim; ++k)
> dst[k] = ~src[k];
> -
> - if (bits % BITS_PER_LONG)
> - dst[k] = ~src[k];
> }
> EXPORT_SYMBOL(__bitmap_complement);
>
> --
> 2.14.1
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-04-11 14:59 [PATCH] lib: micro-optimization for __bitmap_complement() Yury Norov
2018-04-20 13:43 ` Yury Norov
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