Messages in this thread | | | Date | Fri, 29 Dec 2006 21:45:54 -0500 | From | Dave Jones <> | Subject | potential for buffer_head shrinkage. |
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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.
Opinions?
Dave
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