On Thu, Apr 9, 2020 at 2:18 AM Özkan KIRIK <ozkan.ki...@gmail.com> wrote: > > Hello, > > I wonder if it is possible to update dummynet code multi-threading capable > practically? > My idea is below: > - A new sysctl tunable will be defined as > "net.inet.ip.dummynet.thread_count" (default 1) > - To distribute tasks along threads, each sched instance can be assigned to > different thread. > - By default, all schedulers assigned to thread 0 if no thread_id is set. > With a new option named "thr_id" affinity can be set. as below: > ipfw sched 1 config type QFQ (by defaut thr_id = 0) > ipfw sched 2 config type QFQ thr_id 1 > ipfw sched 3 config type QFQ thr_id 2 > ipfw sched 4 config type FIFO thr_id 3 > ipfw sched 5 config type FIFO thr_id 3 ( sched 4 & 5 assigned to same > thread 3 ) > > I think this approach is more easy then completely rewrite or other > solutions. >
This change may not be completely trivial given that dummynet was designed as single threaded and protected by a single lock. If you want to proceed, you should do as follows: - some members of struct dn_parms need to be duplicated for each thread, including prev_t, evheap, curr_time, the locks, and perhaps others. Probably may be useful to create a new struct for them, with a back pointer to the parent dn_parms, and include a refcount. - add another rwlock to protect access to dn_cfg - dummynet_io() does the initial demultiplexing calling dn_ht_find(), currently protected DN_BH_WLOCK(). This could be changed to an RWLOCK and I believe this initial step could be protected by a read lock (maybe there are corner cases where you need to create a new entry so you need to drop the lock, acquire in write mode and retry...) - once the demux has returned a dn_fsk, maybe you can use a refcount to avoid the object being destroyed, release the read lock on dn_cfg.fshash, acquire an exclusive lock on the thread handling the dn_fsk, and proceed from there. - the kernel thread that process the heap should now run each on one instance of the evheap cheers luigi _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
