On Fri, Dec 29, 2006 at 09:45:54PM -0500, Dave Jones wrote: > Looking at struct buffer_head, it seems that b_state > uses at most 15 bits, where it's defined as a 64bit entity > due to it being used by bit_spin_lock and friends. > > Given it's not uncommon for a few hundred thousand of these > to be present, I wonder if it's worth the effort of folding > b_count into the upper bits of b_state, thus shrinking > buffer_head by 16 bits? This would still leave 32 bits > 'wasted' for further bh_state_bits expansion if necessary.
My math here based on a 64 bit compile btw in case that wasn't obvious. 32 bit wouldn't leave room for expansion. Dave -- http://www.codemonkey.org.uk - 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/