From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
<linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] riscv: enable GENERIC_FIND_FIRST_BIT
Date: Thu, 9 Sep 2021 21:49:29 +0800 [thread overview]
Message-ID: <20210909214929.7c2b9ae0@xhacker> (raw)
In-Reply-To: <bbd220c4-b535-d024-6bd3-b620b4702ed3@huawei.com>
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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prev parent reply other threads:[~2021-09-09 13:56 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
2021-09-09 13:49 ` Jisheng Zhang [this message]
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