CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2012/05/30 13:32:19
Modified files:
sys/kern : vfs_bio.c
Log message:
Fix a few issues in the pressure logic when the available buffers run low:
- make sure the buffer reclaiming loop in buf_get() actually does something
but spin, if `backoffpages' is nonzero and all free queues have been drained.
- don't forget to set a poor man's condition variable to nonzero before
tsleeping on it in bufadjust(), otherwise you'll never get woken up.
- don't be too greedy and reassing backoffpages a large amount immediately
after bufadjust() has been called.
This fixes reproduceable hangs seen during heavy I/O (such as `make install'
of many large files, e.g. run in /usr/src/lib with NOMAN=) on systems with
a challenged number of pages (less than a few thousands, total).
Part of this is temporary bandaid until a better pressure logic is devised,
but it's solving an immediate problem. Been in snapshots for a solid month.
