From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Date: Tue, 22 Mar 2022 22:27:58 +0000 Subject: [Intel-wired-lan] [PATCH v2] ice: use min_t() to make code cleaner in ice_gnss In-Reply-To: <20220322112730.482d674d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> References: <20220321135947.378250-1-wanjiabing@vivo.com> <20220322175038.2691665-1-alexandr.lobakin@intel.com> <20220322112730.482d674d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: From: Jakub Kicinski > Sent: 22 March 2022 18:28 > > 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. Not in the cpu clock count tables I've read. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)