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the correct behaviour (sorting by distance from the current head position in the scan direction) and bioq_insert_head() and bioq_insert_tail() have a well defined (and useful) behaviour, especially when intermixed with calls to bioq_disksort(). In particular: - fix a bug in the existing bioq_disksort() that did not use the current head position correctly; - redefine semantics of bioq_insert_head() and bioq_insert_tail(). bioq_insert_tail() can now be used as a barrier between previous and subsequent calls to bioq_disksort(). The code is heavily documented in the source code so please refer to that for the details. Much of this code comes from Fabio Checconi. Also thanks to Kirk for feedback on the (re)definition of bioq_insert_tail(). NOTE: in the current tree there is only a handful of files which intermix calls to bioq_disksort() with bioq_insert_head() and bioq_insert_tail(). The ordering of the queue in these situation was not specified (nor easy to figure out) before, so I doubt any of that code could be affected by the specification of the API. Also note that the current implementation is significantly simpler than the previous one (also used in ata_sort_queue()). It would be useful to reimplement ata_sort_queue() using the same code used in bioq_disksort(). MFC after: 1 week |
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contrib | ||
crypto | ||
etc | ||
games | ||
gnu | ||
include | ||
kerberos5 | ||
lib | ||
libexec | ||
release | ||
rescue | ||
sbin | ||
secure | ||
share | ||
sys | ||
tools | ||
usr.bin | ||
usr.sbin | ||
COPYRIGHT | ||
LOCKS | ||
MAINTAINERS | ||
Makefile | ||
Makefile.inc1 | ||
ObsoleteFiles.inc | ||
README | ||
UPDATING |
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