On Mon, Sep 19, 2016 at 10:32:13PM +0200, Julien Charbon wrote: > > > @ CPU_CLK_UNHALTED_CORE [4653445 samples] > > > > 51.86% [2413083] lock_delay @ /boot/kernel.VSTREAM/kernel > > 100.0% [2413083] __rw_wlock_hard > > 100.0% [2413083] tcp_tw_2msl_scan > > 99.99% [2412958] pfslowtimo > > 100.0% [2412958] softclock_call_cc > > 100.0% [2412958] softclock > > 100.0% [2412958] intr_event_execute_handlers > > 100.0% [2412958] ithread_loop > > 100.0% [2412958] fork_exit > > 00.01% [125] tcp_twstart > > 100.0% [125] tcp_do_segment > > 100.0% [125] tcp_input > > 100.0% [125] ip_input > > 100.0% [125] swi_net > > 100.0% [125] intr_event_execute_handlers > > 100.0% [125] ithread_loop > > 100.0% [125] fork_exit > > The only write lock tcp_tw_2msl_scan() tries to get is a > INP_WLOCK(inp). Thus here, tcp_tw_2msl_scan() seems to be stuck > spinning on INP_WLOCK (or pfslowtimo() is going crazy and calls > tcp_tw_2msl_scan() at high rate but this will be quite unexpected). > > Thus my hypothesis is that something is holding the INP_WLOCK and not > releasing it, and tcp_tw_2msl_scan() is spinning on it. > > If you can, could you compile the kernel with below options: > > options DDB # Support DDB. > options DEADLKRES # Enable the deadlock resolver > options INVARIANTS # Enable calls of extra sanity > checking > options INVARIANT_SUPPORT # Extra sanity checks of internal > structures, required by INVARIANTS > options WITNESS # Enable checks to detect > deadlocks and cycles > options WITNESS_SKIPSPIN # Don't run witness on spinlocks > for speed
Currently this host run with 100% CPU load (on all cores), i.e. enabling WITNESS will be significant drop performance. Can I use only some subset of options? Also, I can some troubles to DDB enter in this case. May be kgdb will be success (not tryed yet)? > And once the issue is reproduce, run in ddb run the below commands: > > show pcpu > show allpcpu > show locks > show alllocks > show lockchain > show allchains > show all trace > > This is to see if the contention is indeed on the tcp_tw_2msl_scan's > INP_WLOCK. _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
