---------- Forwarded message ---------- From: Giuseppe Ghibò <[email protected]> Date: 2015-06-13 1:13 GMT+02:00 Subject: Re: [OM Cooker] [om-general] Community poll about i586 - have your say! To: Per Øyvind Karlsen <[email protected]>
On 12/06/2015 17:02, Per Øyvind Karlsen wrote: Another argument for keeping i586 port is that x86_64 has eliminated virtual mode, ie. i586 build of dosbox is way faster than x86_64 because of this... Also do not forget that people who care about performance, multimedia etc., would most likely not have legacy hardware, so 5-15% would be hugely irrelevant to most of those people. (btw. while some i586 has mmx support, pentium pro has not) Fedora (likely others also, like Ubuntu) has switched to -march=i686 -mtune=atom, I've changed our to -march=i586 -mtune=atom for a while back, so where Fedora doesn't offer an option for legacy hardware (very common in third world countries, schools etc.), we do offer, which allows us to fill a niché market. Would that produce in-order instruction? Or you need -march=atom -mtune=atom for that? Interesting. These i586 class systems still do a good enough job for personal servers, routers, terminal clients (especially think of schools) etc. So offering a merely 5-15% performance increase for systems who are such low performance to begin with, doesn't offer much appeal to users. What I'm saying is that where I've found only non negligible speed up is by enabling the SSE2 (where available), where the boost can be relevant. Every other attempt with MMX, SSE (or from SSE2 to SSE3) -march=i686 I've not seen so perceivable speed up. Personally I've operative a 32bit i5 with PAE and 8GB RAM, as well as ATOM. But in ATOM (is a Atom N450 with 2GB RAM), I use a 64bit because for desktop is faster than i586. There I use for instance fine tuned 32bit application, e.g. firefox32bit over 64bit OS, compiled with -march=i686 -msse -msse2 -mfpmath=sse as this is faster nd consumes less memory than native firefox64bit, I guess because of the 32bit JIT. List of processors without cmov that my research came across: Intel Pentium Intel Pentium MMX Intel Atom Diamonville Intel Atom Silverthorne Intel Atom Linthorne Intel Atom Penwell A few more Intel Atom 32 bit AMD K5 AMD K6 AMD K6-2 AMD K6-3 AMD Geode series: (ie. OLPC, and various others) AMD GeodeGXm AMD GeodeGXLV AMD GeodeGX1 AMD GeodeGX2 AMD GeodeLX (In 2009, comments by AMD indicated that there are no plans for any future micro architecture upgrades to the processor and that there will be no successor; however, the processors will still be available with the planned availability of the Geode LX extending through 2015) Cyrix Cx5x86 Cyrix 6x86 Cyrix MediaGX Cyrix MediaGXi Cyrix MediaGXm Via C3 (which have interesting features such as low power consumption and heat generation, also hardware accelerated random number generator) Via C7(?) (Hardware support for SHA-1 and SHA-256, hardware based "Montgomery multiplier" supporting key sizes up to 32K for public-key cryptography) Via Eden Via Eden ESP Via Eden-N Via Eden ULV WinChip C6 WinChip 2 WinChip 2A WinChip 2B WinChip 3 Nexgen Nx586 Rise mP6 Vortex86 Vortex86SX Vortex86EX2 Vortex86MX+ Vortex86DX Vortex86DX2 The problem is that in theory, but in practice is there someone (I ask for ONE at least in the world), having tried or really using it. From the list above I've/I've had a: - Pentium MMX 133Mhz with 64MB RAM, IDE disks, VIA chipset mobo. In canteen. last time I used was around Mandriva 6.3 or 6.4 more than 10 years ago (now in canteen). Everything newer was not even starting the installer or unusable. Maybe NetBSD :-) - Athlon64 3800 (in canteen). Mobo died. - Celeron 1300 with TUV4X mobo (now in canteen). Tried to overclock, but never worked beyond standard frequency. - Dual Pentium III Coppermine 1000Mhz with Molex silent CPU fans socket 370 with ASUS CUV4X-D mobo, with a GeForce MX400 and 1GB RAM. Worked fine and with VMWare was really cool at that time, but soon proprietary video driver become very slow or unsupported. Tried sometime with nouveau, but wasn't good. In canteen. - Laptop Sony 16" with P4-1.6Ghz and 512MB RAM of 2002 and ATI 7500M videocard. At that time was really fast up to Mandrake 8.1, and the fastest 3D video card with OSS drivers, but then upgrade over upgrade the ATI driver become worst and worst (and fixed), and very very slow (either with EXA o XAA mode) to become unusable with any recent *andriva distro. In canteen. Tried with Peppermint Linux, a bit faster, but not that much usable. In canteen. - Dual Pentium-II 450 on a ASUS P2B-DS...and a SCSI disk spinning since 1998. Still in service with a Mandriva 2009... - Intel core quad Q9550 with a ASUS P5Q Deluxe motherboard and 8GB RAM. CPU still working but motherboard died...; a pity. and I also met of that old: - Cyrix 6x86 - AMD K6-III with SIS chipset and 128MB of memory, worked almost for 14 years as fileserver, bill retriever, and with a Mandriva 7.0, then hardware died. - VIA C3 2.0Ghz. I had on the Dedibox of the French ISP as root server 8 years ago. One of my worst experience, with distro and kernel crashing and panicing a go-go. A nightmare. never met in my career a PentiumPro 200Mhz. They were too expensive when they were new at the time of the P5-MMX, and soon replaced by Pentium-II 233, 266, 333, 400 and 450. Notice that several of these cpus, especially like the Via, Geode etc. are still popular for embedded and for media centers as well due to VPU hardware acceleration etc... Those for media center could be interesting. Certainly I wouldn't recycle any of old P5 or P6 or PII system for building as a router with a noisy and power-hungry PSU, when you can get a lot more from a Raspberry PI which would have a faster memory. Ditto for recycled systems for schools. A friend of mine tried to recycle many P4-3.0 Ghz but most of video cards (matrox, nvidia, etc.) were not working anymore with the drivers provided in the distro, most of motherboard can't boot from USB because of limited BIOS, or even if they can boot, the USB format recognized (maybe eltorito dunno) is not compatible. Or the CD-DVD reader is broken or have lens dirty, and so on...; and even when he was successful, people didn't like it, and wanted the Tablet (even if they couldn't learn ANYTHING from a tablet). in other world what I was only saying is that the only NEW processor and the 32bit CPU line which is used underpowered (despite of all the SIMD sets supported) is the Atom. So please leave as is, i586 compatibility is a feature offered which less and less others do, while i686 offers a meager 5-15% performance increase on systems that far fewer people have interest in. OK, I see your point, thanks for the explaining, which more or less can be: there isn't much to gain in changing that, because if the system is unusable because too slow, it certainly wouldn't be two flags changing in getting it super-responsive or usable for day-to-day usage, but there is much more to loose, in dropping the i586 support. Bye Giuseppe.
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