Messages in this thread | | | Date | Wed, 26 Jan 2000 14:19:35 +0100 | From | Jamie Lokier <> | Subject | Re: Preventing gcc from aligning stack??? |
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David Weinehall wrote: > > > sched.c:77: warning: alignment of `aligned_data' is greater than maximum > > > object file alignment > > > > That's not i386 is it? > > 486.
Hmm. I'm surprised. Linux 2.3.x only compiles in ELF, and ELF permits big alignments. Oddness.
> > Linux uses larger alignments for some things that should be aligned to a > > cache line, either to reduce SMP inter-processor traffic or simply > > because it's faster to read fewer cache lines for some critical things. > > I doubt this is a good idea on 386's/486's, but I might be wrong...
On 486s it's a good idea because they have a cache. cf. Recent patch from IBM which speeds up the scheduler simply be moving some memory accesses to within a cache line. A smaller alignment value might be more suitable for a 486 though. Some nominal 386s have a cache too.
enjoy, -- Jamie
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