linux-kernel - Re: [PATCH][next] scsi: scsi_debug: make read-only arrays static const

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Message-ID: <64ec6c5e-5eb3-4db8-9540-7679ac694c11@gmail.com>
Date: Tue, 29 Jul 2025 20:49:07 +0100
From: "Colin King (gmail)" <colin.i.king@...il.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
 "James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
 "Martin K . Petersen" <martin.petersen@...cle.com>,
 linux-scsi@...r.kernel.org
Cc: kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] scsi: scsi_debug: make read-only arrays static
 const

On 29/07/2025 18:45, Christophe JAILLET wrote:
> Le 29/07/2025 à 08:49, Colin Ian King a écrit :
>> Don't populate the read-only arrays on the stack at run time, instead
>> make them static const. Also reduces overall size.
>>
>> before:
>>     text       data        bss        dec        hex    filename
>>   367439      89582       5952     462973      7107d    drivers/scsi/ 
>> scsi_debug.o
>>
>> after:
>>     text       data        bss        dec        hex    filename
>>   365847      90702       5952     462501      70ea5    drivers/scsi/ 
>> scsi_debug.o
> 
> Hi,
> 
> out of curiosity, any idea why 'data' increase?

Because the arrays are being stored in the data section rather than on 
the stack.

> 
> All my constification patches lead to data reduction.
> 
>>
>> (gcc 14.2.0, x86-64)
> 
> (same kind of behavior with 15.1.1)
> 
> 
> CJ

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