Thread (4 messages) 4 messages, 2 authors, 2021-09-09

Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT

From: Jisheng Zhang <hidden>
Date: 2021-09-09 14:39:03
Also in: lkml

On Thu, 9 Sep 2021 08:58:31 +0800
Kefeng Wang [off-list ref] wrote:
On 2021/9/8 23:04, Jisheng Zhang wrote:
quoted
Hi Palmer,

On Sun, 18 Jul 2021 00:14:23 +0800
Jisheng Zhang wrote:
 
quoted
From: Jisheng Zhang <jszhang@kernel.org>

riscv doesn't implement architecture-optimized bitsearching functions
such as find_first_{zero}_bit() etc.

When GENERIC_FIND_FIRST_BIT=n, find_first_bit() is implemented with
find_next_bit() which is less efficient. Enable GENERIC_FIND_FIRST_BIT
for riscv to get more optimized find_first_bit() implementation, an
initial test(lib/find_bit_benchmark) shows find_first_bit() performance
is improved by nearly 32%.  
It seems this patch is missed. Is it possible to pick it up for 2nd 5.15-rc1 PR?

Thanks  
It is enabled unconditionally by following commit

commit dbbccfe505ef8fae804677abf0564c1e07479102

Author: Yury Norov [off-list ref]
Date:   Tue Aug 24 09:59:56 2021 +1000

     arch: remove GENERIC_FIND_FIRST_BIT entirely
Aha, thanks for the information. After Yury's commit, this patch
is useless now.

thanks


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