All lock-free queues may allocate a padding dead value at the end of a page. This may be not necessary for single-producer queues

[giucamp]

This padding in general is necessary to force the lase value to appear always at the same offset from the beginning of the page, so that all threads can agree on where the CAS game should be played. For single producer queues this is not necessary, so the page-switch may be simplified.