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From: Hongbo Li <lihongbo22@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: <kees@kernel.org>, <andy@kernel.org>, <trondmy@kernel.org>,
	<anna@kernel.org>, <gregkh@linuxfoundation.org>,
	<linux-hardening@vger.kernel.org>, <linux-mm@kvack.org>,
	<linux-nfs@vger.kernel.org>
Subject: Re: [PATCH -next v3 1/3] lib/string_choices: Add str_true_false()/str_false_true() helper
Date: Wed, 28 Aug 2024 11:49:51 +0800	[thread overview]
Message-ID: <a6ea03c9-f92b-4faa-b924-8df58484fb13@huawei.com> (raw)
In-Reply-To: <20240827202204.b76c0510bf44cdfb6d3a74bd@linux-foundation.org>



On 2024/8/28 11:22, Andrew Morton wrote:
> On Wed, 28 Aug 2024 09:48:21 +0800 Hongbo Li <lihongbo22@huawei.com> wrote:
> 
>>> This might result in copies of the strings "true" and "false" being
>>> generated for every .c file which uses this function, resulting in
>>> unnecessary bloat.
>>>
>>> It's possible that the compiler/linker can eliminate this duplication.
>>> If not, I suggest that every function in string_choices.h be uninlined.
>> The inline function is in header file, it will cause code expansion. It
>> should avoid the the copies of the strings.
> 
> Sorry, I don't understand your reply.
> 
I mean this is a inline function (and tiny enough), the compiler will do 
the code expansion and some optimizations.
> Anything which is calling these functions is not performance-sensitive,
> so optimizing for space is preferred.  An out-of-line function which
> returns a const char * will achieve this?
I think this helper can achieve this. Because it is tiny enough, the 
compiler will handle this like #define macro (do the replacement) 
without allocating extra functional stack. On the contrary, if it is 
implemented as a non-inline function, it will cause extra functional 
stack when it was called every time. And it also should be implemented 
in a source file (.c file), not in header file(.h file).

Thanks,
Hongbo


  reply	other threads:[~2024-08-28  3:50 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-27  2:45 [PATCH -next v3 0/3] " Hongbo Li
2024-08-27  2:45 ` [PATCH -next v3 1/3] lib/string_choices: " Hongbo Li
2024-08-27 23:42   ` Andrew Morton
2024-08-28  1:48     ` Hongbo Li
2024-08-28  3:22       ` Andrew Morton
2024-08-28  3:49         ` Hongbo Li [this message]
2024-08-28 20:25           ` Andrew Morton
2024-08-29  1:12             ` Hongbo Li
2024-09-05 16:51             ` (subset) " Kees Cook
2024-08-28 12:59     ` Andy Shevchenko
2024-08-27  2:45 ` [PATCH -next v3 2/3] mm: make use of str_true_false helper Hongbo Li
2024-08-27  2:45 ` [PATCH -next v3 3/3] nfs make use of str_false_true helper Hongbo Li
2024-08-27  3:33   ` Matthew Wilcox
2024-08-27  6:15     ` Hongbo Li

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