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27 March 2024, 02:37:15 UTC
Revision 8c0863403f109a43d7000b4646da4818220d501f authored by Linus Torvalds on 16 November 2007, 00:41:52 UTC, committed by Linus Torvalds on 16 November 2007, 00:41:52 UTC 
dirty page balancing: Get rid of broken unmapped_ratio logic
 
This code harks back to the days when we didn't count dirty mapped
pages, which led us to try to balance the number of dirty unmapped pages
by how much unmapped memory there was in the system.

That makes no sense any more, since now the dirty counts include the
mapped pages.  Not to mention that the math doesn't work with HIGHMEM
machines anyway, and causes the unmapped_ratio to potentially turn
negative (which we do catch thanks to clamping it at a minimum value,
but I mention that as an indication of how broken the code is).

The code also was written at a time when the default dirty ratio was
much larger, and the unmapped_ratio logic effectively capped that large
dirty ratio a bit.  Again, we've since lowered the dirty ratio rather
aggressively, further lessening the point of that code.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent adea27f
History
Tip revision: 8c0863403f109a43d7000b4646da4818220d501f authored by Linus Torvalds on 16 November 2007, 00:41:52 UTC
dirty page balancing: Get rid of broken unmapped_ratio logic
Tip revision: 8c08634
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.gitignore -rw-r--r-- 628 bytes
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