Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 6/9] mm/z3fold: move decrement of pool->pages_nr into __release_z3fold_page() | Date | Wed, 2 Mar 2022 09:12:02 +0000 |
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> > Atomic operations aren't magic. > > Atomic operations are (at best) one slow locked bus cycle. > > Acquiring a lock is the same. > > Releasing a lock might be cheaper, but is probably a locked bus cycle. > > > > So if you use state_lock to protect pages_nr then you lose an atomic > > operation for the decrement and gain one (for the unlock) in the increment. > > That is even or maybe a slight gain. > > OTOH a 64bit atomic is a PITA on some 32bit systems. > > (In fact any atomic is a PITA on sparc32.) > > It's actually *stale_lock* and it's very misleading to use it for this. > I would actually like to keep atomics but I have no problem with > making it 32-bit for 32-bit systems. Would that work for you guys?
It would be better to rename the lock.
David
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