percpu_counter: new function percpu_counter_sum_and_set

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Delayed allocation need to check free blocks at every write time.
percpu_counter_read_positive() is not quit accurate. delayed
allocation need a more accurate accounting, but using
percpu_counter_sum_positive() is frequently is quite expensive.

This patch added a new function to update center counter when sum
per-cpu counter, to increase the accurate rate for next
percpu_counter_read() and require less calling expensive
percpu_counter_sum().

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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Mingming Cao 2008-07-11 19:27:31 -04:00 • committed by Theodore Ts'o

parent 64769240bd

commit e8ced39d5e

3 changed files with 16 additions and 5 deletions

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include/linux/percpu_counter.h

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