* [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
@ 2021-07-17 16:14 Jisheng Zhang
2021-09-08 15:04 ` Jisheng Zhang
0 siblings, 1 reply; 4+ messages in thread
From: Jisheng Zhang @ 2021-07-17 16:14 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou; +Cc: linux-riscv, linux-kernel
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%.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
arch/riscv/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 8fcceb8eda07..7ebc54c5c245 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -47,6 +47,7 @@ config RISCV
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_EARLY_IOREMAP
+ select GENERIC_FIND_FIRST_BIT
select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
select GENERIC_IOREMAP
select GENERIC_IRQ_MULTI_HANDLER
--
2.32.0
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
2021-07-17 16:14 [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT Jisheng Zhang
@ 2021-09-08 15:04 ` Jisheng Zhang
2021-09-09 0:58 ` Kefeng Wang
0 siblings, 1 reply; 4+ messages in thread
From: Jisheng Zhang @ 2021-09-08 15:04 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou; +Cc: linux-riscv, linux-kernel
Hi Palmer,
On Sun, 18 Jul 2021 00:14:23 +0800
Jisheng Zhang wrote:
> 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
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
> arch/riscv/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 8fcceb8eda07..7ebc54c5c245 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -47,6 +47,7 @@ config RISCV
> select GENERIC_ATOMIC64 if !64BIT
> select GENERIC_CLOCKEVENTS_BROADCAST if SMP
> select GENERIC_EARLY_IOREMAP
> + select GENERIC_FIND_FIRST_BIT
> select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
> select GENERIC_IOREMAP
> select GENERIC_IRQ_MULTI_HANDLER
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
2021-09-08 15:04 ` Jisheng Zhang
@ 2021-09-09 0:58 ` Kefeng Wang
2021-09-09 13:49 ` Jisheng Zhang
0 siblings, 1 reply; 4+ messages in thread
From: Kefeng Wang @ 2021-09-09 0:58 UTC (permalink / raw)
To: Jisheng Zhang, Paul Walmsley, Palmer Dabbelt, Albert Ou
Cc: linux-riscv, linux-kernel
On 2021/9/8 23:04, Jisheng Zhang wrote:
> Hi Palmer,
>
> On Sun, 18 Jul 2021 00:14:23 +0800
> Jisheng Zhang wrote:
>
>> 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 <yury.norov@gmail.com>
Date: Tue Aug 24 09:59:56 2021 +1000
arch: remove GENERIC_FIND_FIRST_BIT entirely
>
>> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
>> ---
>> arch/riscv/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 8fcceb8eda07..7ebc54c5c245 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -47,6 +47,7 @@ config RISCV
>> select GENERIC_ATOMIC64 if !64BIT
>> select GENERIC_CLOCKEVENTS_BROADCAST if SMP
>> select GENERIC_EARLY_IOREMAP
>> + select GENERIC_FIND_FIRST_BIT
>> select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
>> select GENERIC_IOREMAP
>> select GENERIC_IRQ_MULTI_HANDLER
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
> .
>
_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
2021-09-09 0:58 ` Kefeng Wang
@ 2021-09-09 13:49 ` Jisheng Zhang
0 siblings, 0 replies; 4+ messages in thread
From: Jisheng Zhang @ 2021-09-09 13:49 UTC (permalink / raw)
To: Kefeng Wang
Cc: Paul Walmsley, Palmer Dabbelt, Albert Ou, linux-riscv, linux-kernel
On Thu, 9 Sep 2021 08:58:31 +0800
Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
> On 2021/9/8 23:04, Jisheng Zhang wrote:
> > Hi Palmer,
> >
> > On Sun, 18 Jul 2021 00:14:23 +0800
> > Jisheng Zhang wrote:
> >
> >> 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 <yury.norov@gmail.com>
> 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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^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-07-17 16:14 [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT Jisheng Zhang
2021-09-08 15:04 ` Jisheng Zhang
2021-09-09 0:58 ` Kefeng Wang
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