On Wed, 26 Jul 2006, Manfred Spraul wrote: > Christoph Lameter wrote: > > > A slab user is setting alignment in order to optimize performance not for > > correctness. Most users that I know of can live with misalignments. If that > > would not be the case then this code would never have worked. > > > > Which users do you know that set align and that can live with misalignments? > As I wrote, there are no such users in my (i386) kernel. The users of SLAB_HWCACHE_ALIGN can live with that. Systems running with slab debugging on must be very buggy at this point or we were very lucky: The list is a bit strange: >* the pmd structure (4096: hardware requirement) It is already exempted from debug since the size is 4096. >* the pgd structure (32 bytes: hardware requirement) We were lucky on that one in the past? This should break. >* the task structure (16 byte. fxsave) Would only break if floating point is used I think. >* sigqueue, pid: both request 4 byte alignment (based on __alignof__()). >Doesn't affect debugging. So also not relevant. We now want to say that SLAB_HWCACHE_ALIGN is only a suggestion to be disposed of if debug is on whereas an explicitly specified alignment must be enforced? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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