On Fri, 25 Feb 2000, Stephen C. Tweedie wrote:

On Fri, 25 Feb 2000 00:30:59 +0100 (CET), Rik van Riel
[off-list ref] said:

quoted

The patch should apply to any 2.2 or 2.3 kernel, but for
2.3 it'll have the interesting side effect of nullifying
the (minimal) page aging that's going on there.

Have you actually tested the impact of this under a variety of
load conditions?  In the past we have seen such apparently trivial
changes completely break the VM balance under certain loads.

The PG_referenced bit isn't used for anything except for
NRU/LRU page reclaiming in shrink_mmap().

However, shrink_mmap() will skip over any pages that are
still mapped by processes _and_ when we unmap the page
from the (next to) last user we set the PG_referenced bit.

The PG_referenced bit is also not used at all by shrink_mmap(),
unless (page->count == 1); shm_swap() doesn't use the referenced
bit at all.

regards,

Rik
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