On Fri 2017-06-23 12:20:11, Luis R. Rodriguez wrote: > 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, and then throttling them in, > one by one. > > This throttling enables requests over the kmod concurrent limit to > be processed once a pending request completes. Only the first item > queued up to wait is woken up. The assumption here is once a task > is woken it will have no other option to also kick the queue to check > if there are more pending tasks -- regardless of whether or not it > was successful. > > By throttling and processing only max kmod concurrent tasks we ensure > we avoid unexpected fatal request_module() calls, and we keep memory > consumption on module loading to a minimum. > > 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 0m16.523s > user 0m0.879s > sys 0m8.977s > > time ./kmod.sh -t 0009 > real 0m56.080s > user 0m0.717s > sys 0m10.324s > > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> All the changes look fine to me. They make perfect sense. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
