netdev - Re: [PATCH v2] ice: use min_t() to make code cleaner in ice

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Date:   Tue, 22 Mar 2022 11:27:30 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     'Alexander Lobakin' <alexandr.lobakin@...el.com>,
        'Wan Jiabing' <wanjiabing@...o.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ice: use min_t() to make code cleaner in ice_gnss

On Tue, 22 Mar 2022 18:12:08 +0000 David Laight wrote:
> > > Oh FFS why is that u16?
> > > Don't do arithmetic on anything smaller than 'int'  
> > 
> > Any reasoning? I don't say it's good or bad, just want to hear your
> > arguments (disasms, perf and object code measurements) etc.  
> 
> Look at the object code on anything except x86.
> The compiler has to add instruction to mask the value
> (which is in a full sized register) down to 16 bits
> after every arithmetic operation.

Isn't it also slower on some modern x86 CPUs?
I could have sworn someone mentioned that in the past.