On Mon, 2002-11-04 at 19:21, Lucas Albers wrote: > Use the stock kernel. > I'd like to see some benchmarks that show recompiling the kernel is > worthwhile for desktops, (Servers have other issues.) > > User:Hey sysadmin this kernel is 5% faster, but it locks up every 2 > weeks. > Come and fix it.... I wrote a numerical analysis who was published in february 1999 and basically you don't gain 5%. It is closer to 1.5% to 2.5% and this when you are running kernel code (when you are running user mode code it is unaffected). And since 2002 machines are much bigger than the 32 meg box I used as an example the memory savings brought by a kernel compile are still more irrelevant > > I'd rather just have a kernel that works, computers are disk-bound > anyways, recompiling with a few extra optimizations just isn't > worthwhile. > > > > > --Luke > > --Computer Science Sysadmin, MSU Bozeman > > --admin(AT)cs.montana.edu 994-3931 > > > -----Original Message----- > > From: psyche-list-admin@redhat.com > [mailto:psyche-list-admin@redhat.com] > > On Behalf Of Jakub Jelinek > > Sent: Wednesday, October 23, 2002 3:36 PM > > To: psyche-list@redhat.com > > Subject: Re: i386 kernel not included? > > > > On Wed, Oct 23, 2002 at 11:51:46AM -0500, Thomas Dodd wrote: > > > > > > > > > Thomas Dodd wrote: > > > > But if most pre i686 CPUS (pre PPro/PII/Athlon) run the i386 code > > > > mix faster than the pentium mix, why not supply the i386 mix. > > > > I woul thing there are more 486s, P/MMX, K5, K6, and Cyrix CPUs > > > > still in use than Pentiums (pre MMX). > > > > > > > > > A test using a simple C source file: > > > > > > -march=i386 -mcpu=i586 and -march=i586 -mcpu=i586 > > > were the same. > > > > > > -march=i386 -mcpu=i586 and -march=i386 -mcpu=i686 > > > had a lot of differences. The instruction mix was very different. > > > > > > -march=i386 -mcpu=i586 and -march=i386 -mcpu=athlon > > > Very different to. > > > > > > -march=i386 -mcpu=i686 was the same as -march=i386 -mcpu=athlon > > > Most interesting to me, > > > The mix is different. > > > > > > example > > > i686 athlon > > > movl -24(%edp), %edx andl -24(%edp), %eax > > > andl %edx, %eax > > > > > > > > > movl %eax, %edx imull $100, %eax, %edx > > > movl %edx, %eax > > > sall $2, %eax > > > addl %edx, %eax > > > leal 0(,%eax,4), %edx > > > addl %edx, %eax > > > leal 0(,%eax,4), %edx > > > > Do you have testcase and exact options for this? > > $edx = 100*$eax is with -O2 -mcpu=i686: > > leal (%eax,%eax,4), %edx > > leal (%edx,%edx,4), %edx > > sall $2, %edx > > for me. > > > > Jakub > > > > > > > > -- > > Psyche-list mailing list > > Psyche-list@redhat.com > > https://listman.redhat.com/mailman/listinfo/psyche-list > > > > -- > Psyche-list mailing list > Psyche-list@redhat.com > https://listman.redhat.com/mailman/listinfo/psyche-list > -- Psyche-list mailing list Psyche-list@redhat.com https://listman.redhat.com/mailman/listinfo/psyche-list
