On Mon, Jun 26, 2017 at 01:38:31PM +0200, Petr Mladek wrote: > 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. Thanks, I'll peg a Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Luis -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
