From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,56525db28240414a X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Received: by 10.66.76.162 with SMTP id l2mr1257710paw.42.1343317300058; Thu, 26 Jul 2012 08:41:40 -0700 (PDT) Received: by 10.68.219.170 with SMTP id pp10mr384862pbc.1.1343312590489; Thu, 26 Jul 2012 07:23:10 -0700 (PDT) Path: p10ni65138561pbh.1!nntp.google.com!u4no506182pbs.0!news-out.google.com!b9ni61666166pbl.0!nntp.google.com!npeer02.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!novia!news-peer1!btnet!zen.net.uk!hamilton.zen.co.uk!xlned.com!feeder5.xlned.com!ramfeed-1.ams.xsnews.nl!feed.xsnews.nl!border-3.ams.xsnews.nl!border3.nntp.ams.giganews.com!border1.nntp.ams.giganews.com!border4.nntp.ams.giganews.com!border2.nntp.ams.giganews.com!nntp.giganews.com!newsfeed.straub-nv.de!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!usenet-fr.net!proxad.net!feeder1-2.proxad.net!74.125.178.16.MISMATCH!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail From: Keean Schupke Newsgroups: comp.lang.ada Subject: Re: Efficient Sequential Access to Arrays Date: Sun, 22 Jul 2012 08:50:52 -0700 (PDT) Organization: http://groups.google.com Message-ID: <9b2240eb-0d0e-4233-880b-11f23f5ca314@googlegroups.com> References: <9d4d4463-4c7e-40f4-a167-933eb056c6a5@googlegroups.com> <5007ecf3$0$9507$9b4e6d93@newsspool1.arcor-online.net> <3dbfa883-54c8-4269-a567-26dde8ead4cd@googlegroups.com> <72dbbd45-320b-436a-9d81-fcb6d02504e1@googlegroups.com> <500a9811$0$6639$9b4e6d93@newsspool2.arcor-online.net> <37aca7fe-e367-4a37-8d8b-babd75f264d1@googlegroups.com> NNTP-Posting-Host: 82.44.19.199 Mime-Version: 1.0 X-Trace: posting.google.com 1342972339 29057 127.0.0.1 (22 Jul 2012 15:52:19 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Sun, 22 Jul 2012 15:52:19 +0000 (UTC) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=82.44.19.199; posting-account=T5Z2vAoAAAB8ExE3yV3f56dVATtEMNcM User-Agent: G2/1.0 X-Original-Bytes: 3040 X-Received-Bytes: 3327 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Date: 2012-07-22T08:50:52-07:00 List-Id: On Saturday, 21 July 2012 22:38:49 UTC+1, Dennis Lee Bieber wrote: > On Sat, 21 Jul 2012 09:14:11 -0700 (PDT), Keean Schupke declaimed the fol= lowing in comp.lang.ada: >=20 >=20 > > Here are my results: > >=20 > > 24 byte nodes (all integers) : 42k sims per second > > 16 byte nodes (all short_ints) : 40k sims per second > > 32 byte nodes (all integers + padding) : 42k sims per second. > >=20 > > So 32bit integers seem faster than 16bit integers, and as the whole = data set fits in the cache (its less than 10kbytes) the size of the nodes d= oes not really affect performance. > > > Presuming the computer has a 32-bit bus, those results are viable... > The 16-bit data may require loading 32-bit words followed by shifting > and/or masking the undesired part. > --=20 > Wulfraed Dennis Lee Bieber AF6VN The CPU is 64bits wide, the cache lines are 64 bytes long. The CPU is conne= cted to the cache by a bus much wider than 64 bits (512 bits I think) and t= he cache is several megabytes so the working set easily fits in the bus. Th= e main memory controller has multiple channels operating at 32 bit width bu= t clocked independently of the processor so it is better to think in terms = of memory bandwidth and page-miss cost of the DRAM. Cheers, Keean.