From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: <linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
Date: Thu, 9 Sep 2021 08:58:31 +0800 [thread overview]
Message-ID: <bbd220c4-b535-d024-6bd3-b620b4702ed3@huawei.com> (raw)
In-Reply-To: <20210908230427.3a92fb87@xhacker>
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
> .
>
next prev parent reply other threads:[~2021-09-09 0:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2021-09-09 13:49 ` Jisheng Zhang
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