linux-kernel - Re: [PATCH v2 1/5] csky: Remove custom asm/atomic.h implementation

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Message-ID: <CAJF2gTSLLC8yLzLNkuRwLXBihs3uy9TXVVKRpEF9mM4nN4FopQ@mail.gmail.com>
Date:   Thu, 21 Jan 2021 15:10:48 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-csky@...r.kernel.org,
        linux-arch <linux-arch@...r.kernel.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Arnd Bergmann <arnd@...nel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH v2 1/5] csky: Remove custom asm/atomic.h implementation

Hi Peter,

On Thu, Jan 7, 2021 at 7:19 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Sun, Dec 20, 2020 at 03:39:19PM +0000, guoren@...nel.org wrote:
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > Use generic atomic implementation based on cmpxchg. So remove csky
> > asm/atomic.h.
>
> Clarification would be good. Typically cmpxchg() loops perform
> sub-optimal on LL/SC architectures, due to the double loop construction.

Yes, you are right. But I still want to use comm cmpxchg instead of my
implementation. Maybe in the future, we'll optimize it back.

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/