linux-kernel - Re: [PATCH v2] bit_spinlock: introduce smp_cond_load

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Date:   Tue, 6 Nov 2018 20:33:56 +0800
From:   Gao Xiang <gaoxiang25@...wei.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     Will Deacon <will.deacon@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>, Miao Xie <miaoxie@...wei.com>,
        Chao Yu <chao@...nel.org>
Subject: Re: [PATCH v2] bit_spinlock: introduce smp_cond_load_relaxed

Hi Peter,

On 2018/11/6 20:27, Peter Zijlstra wrote:
> On Tue, Nov 06, 2018 at 07:36:41PM +0800, Gao Xiang wrote:
>> IMO, to use wrapped up function for the detailed scenario could be better than
>> open-coded all the time (eg. do cpu_relax(); while(...)) since it could be
>> optimizated even more for the specific architecture...
> That's the whole point though; if this actually matters, you're doing it
> wrong.

I cannot fully understand your point...Sorry about my English...

To the point, you mean it is much better to fix it as Will suggested before or
leave the matter as it is since the performance of bit_spinlock itself doesn't matter?

Thanks in advance.

Thanks,
Gao Xiang