Deutsch English Français Italiano |
<2024May30.170435@mips.complang.tuwien.ac.at> View for Bookmarking (what is this?) Look up another Usenet article |
Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: anton@mips.complang.tuwien.ac.at (Anton Ertl) Newsgroups: comp.arch Subject: Re: architectural goals, Byte Addressability And Beyond Date: Thu, 30 May 2024 15:04:35 GMT Organization: Institut fuer Computersprachen, Technische Universitaet Wien Lines: 48 Message-ID: <2024May30.170435@mips.complang.tuwien.ac.at> References: <v0s17o$2okf4$2@dont-email.me> <v36bva$10k3v$2@dont-email.me> <2024May29.090435@mips.complang.tuwien.ac.at> <v38opv$1gsj2$3@dont-email.me> <v38riq$1aqo$1@gal.iecc.com> <2024May30.142717@mips.complang.tuwien.ac.at> <v39vn6$1n8gd$1@dont-email.me> Injection-Date: Thu, 30 May 2024 17:27:18 +0200 (CEST) Injection-Info: dont-email.me; posting-host="46db1f935b2b8b941d470a80861909b8"; logging-data="1847694"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX187s/CfjcCipHtm5hGojrFr" Cancel-Lock: sha1:IRgXDoaLBn8Vn4fSa6neIXOYmj8= X-newsreader: xrn 10.11 Bytes: 3340 Thomas Koenig <tkoenig@netcologne.de> writes: >Anton Ertl <anton@mips.complang.tuwien.ac.at> schrieb: > >> It's still marketing. I have listened to several talks about >> converting S/360 programs to C code that can be run on arbitrary >> hardware, and IBM's audience hears about such things, too, so IBM's >> sales force has to provide reasons for not jumping ship. And all >> these new features that sound like they are useful are such reasons. >> Things like decimal FP and CU14. >> >> The fact that these feature provide no actual benefit is their best >> property: > >No actual benefit? > >If you make such a strong statement, I assume that you have done a >thorough analysis of this feature for typical mainframe workloads >and can support your claims with benchmarks. > >Care to show exactly what you did, and what the results were? It provides no actual benefit, because UTF-32 provides no actual benefit. In nearly all code you don't need code points. Dealing with data as mostly opaque strings in UTF-8 is less complicated *and* more efficient than converting them to UTF-32, working with UTF-32 strings, and converting back (even if the conversion was very cheap). Of course there are API mistakes (like Python3) that lead to some usage of UTF-32, but even on Intel and AMD CPUs where Python3 code probably consumes more cycles than on other hardware, that usage has not been enough to add instructions like CU14. IBM z also has CU12 and CU21 (for converting between UTF-8 and UTF-16), and such instructions could see some usage in environments where UTF-16 is big, such as Java, JavaScript, and Windows, but even in CPUs by Intel and AMD (with lots of Windows and JavaScript) and ARM (Android, i.e., Java) this has not led to instructions for converting between UTF-8 and UTF-16. Concerning benchmarks, last I heard IBM forbids benchmarking z hardware. Until they change this, I'll assume their z hardware is abysmally slow and any benchmarking would result in embarrassment, IBM knows this and that's why they forbid benchmarking. - anton -- 'Anyone trying for "industrial quality" ISA should avoid undefined behavior.' Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>