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CyberLeo.Net >> Repos - FreeBSD/FreeBSD.git/commit
sx: port over writer starvation prevention measures from rwlock
A constant stream of readers could completely starve writers and this is not
a hypothetical scenario.
The 'poll2_threads' test from the will-it-scale suite reliably starves writers
even with concurrency < 10 threads.
The problem was run into and diagnosed by dillon@backplane.com
There was next to no change in lock contention profile during -j 128 pkg build,
despite an sx lock being at the top.
Tested by: pho