kmod: throttle kmod thread limit
If we reach the limit of modprobe_limit threads running the next
request_module() call will fail. The original reason for adding
a kill was to do away with possible issues with in old circumstances
which would create a recursive series of request_module() calls.
We can do better than just be super aggressive and reject calls
once we've reached the limit by simply making pending callers wait
until the threshold has been reduced.
The only difference is the clutch helps with avoiding making
request_module() requests fatal more often. With x86_64 qemu,
with 4 cores, 4 GiB of RAM it takes the following run time to
run both tests:
time kmod.sh -t 0008
real 0m14.066s
user 0m1.403s
sys 0m5.837s
time kmod.sh -t 0009
real 0m53.928s
user 0m1.271s
sys 0m7.343s
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
2 files changed
