linux-kernel - Re: [PATCH v3 4/4] x86/mce: Avoid unnecessary padding in struct mce

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Message-ID: <56166aca-8605-ec6b-6ccf-d76565518421@amd.com>
Date:   Tue, 22 Feb 2022 15:02:50 -0600
From:   "Koralahalli Channabasappa, Smita" <skoralah@....com>
To:     Borislav Petkov <bp@...en8.de>,
        Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
Cc:     x86@...nel.org, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>,
        Yazen Ghannam <yazen.ghannam@....com>
Subject: Re: [PATCH v3 4/4] x86/mce: Avoid unnecessary padding in struct
 mce_bank

Hi Boris,

On 2/22/22 9:36 AM, Borislav Petkov wrote:

> On Fri, Feb 11, 2022 at 04:34:42PM -0600, Smita Koralahalli wrote:
>> Include struct mce_bank member "init" in the bitfield by changing its type
>> from bool to get rid of unnecessary padding and to reduce the overall
>> struct size.
>>
>> Outputs collected before and after the change.
>>
>> $ pahole -C mce_bank arch/x86/kernel/cpu/mce/core.o
>>
>> before:
>>
>> 	/* size: 24, cachelines: 1, members: 5 */
>> 	/* bit holes: 1, sum bit holes: 62 bits */
>> 	/* bit_padding: 2 bits */
>> 	/* last cacheline: 24 bytes */
>>
>> after:
>>
>> 	/* size: 16, cachelines: 1, members: 5 */
>> 	/* last cacheline: 16 bytes */
> I don't mind cleanups like that but when you send them as part of a set
> adding new functionality, the usual rule is to put bug fixes, cleanups,
> improvements, etc to the existing code *first*, and then, ontop you add
> your new code.
>
> IOW, this patch should be first in your set.
>
> Thx.
>
Thanks for letting me know.
Will correct and move it to first in the next series.

Thanks,
Smita