On Wed, Aug 25, 2004 at 12:23:54AM -0500, Adam Majer wrote: > Matt Zimmerman wrote: > > >On Mon, Aug 09, 2004 at 02:56:15PM -0500, Adam Majer wrote: > > > > > > > >>There is no more 586 kernel though. Not even the regular one. The 386 > >>version is quite slower on a Pentium MMX than an optimized one. > >> > >> > > > >Have you measured this? > > > > > > > With my stop watch. Really. KDE was at least twice as slow with a 386 > kernel than a 586mmx kernel. There is a *huge* performance penalty if > one is running a 386 kernel. I have tried this on a Pentium 200 MMX with > 196MB. With slow machines like this, the difference between a 386 and > 586 can be seconds to start things like terminal or Konqueror. It is > actually more than a minute booting up. The system is essentially > unusable with a 386 kernel, but it is still running at a steady pace > under a 586mmx kernel. This is a *5*86 chip, and not a 686, right? This is not implausible; the 586 was a *disaster* in hindsight, and an oddball in an otherwise tidy series of chips. I believe the problem lies with the pipeline scheduling; at any rate, you want 586-targetted code on a 586 and 486-targetted on anything else. You also want to throw your 586 in the bin. On the other hand, there are at least half a dozen other things that could possibly be responsible for this, and it doesn't sound like you've ruled any of them out. Certainly this is not compelling evidence; you'd have to analyse exactly *why* it made a difference. > I'm not complaining that there is no 2.6.x 586 or 586-mmx kernels since > I can just rebuild one. But there is a huge performance loss running a > 386 kernel on anything else than a 386 or maybe a 486 (but I haven't > tried a 486). This, however, is *not* true. If you have a *6*86 then the design flaw was fixed and the problem does not occur. What's more, a 586 isn't much happier about 686-targetted code than it is about 386-targetted code. And nothing else likes running 586-targetted code - it can be slower than 486-targetted code in some circumstances, when running on a 686. The difference between 486-targetted and 686-targetted, on a 686, is small to nonexistent. -- .''`. ** Debian GNU/Linux ** | Andrew Suffield : :' : http://www.debian.org/ | `. `' | `- -><- |
Attachment:
signature.asc
Description: Digital signature