Messages in this thread | | | Date | Tue, 26 Apr 2005 23:28:12 +0400 | From | Evgeniy Polyakov <> | Subject | Re: [1/1] connector/CBUS: new messaging subsystem. Revision number next. |
| |
On Tue, 26 Apr 2005 14:06:36 -0500 Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> On 4/26/05, Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote: > > On Tue, 26 Apr 2005 13:42:10 -0500 > > Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote: > > > Yes, that woudl work, although I would urge you to implement a message > > > queue for callbacks (probably limit it to 1000 messages or so) to > > > allow bursting. > > > > It already exist, btw, but not exactly in that way - > > we have skb queue, which can not be filled from userspace > > if pressure is so strong so work queue can not be scheduled. > > It is of course different and is influenced by other things > > but it handles bursts quite well - it was tested on both > > SMP and UP machines with continuous flows of forks with > > shape addon of new running tasks [both fith fork bomb and not], > > so I think it can be called real bursty test. > > > > Ok, hear me out and tell me where I am wrong: > > By default a socket can receive at least 128 skbs with 258-byte > payload, correct? That means that user of cn_netlink_send, if started > "fresh", 128 average - size connector messages. If sender does not > want to wait for anything (unlike your fork tests that do schedule) > that means that 127 of those 128 messages will be dropped, although > netlink would deliver them in time just fine. > > What am I missing?
Concider netlink_broadcast - it delivers skb to the kernel listener directly to the input callback - no queueing actually, the same is for netlink_unicast - so in-kernel users are always called synchronously. send() [sys_send()] system call(which btw as syscall does schedule too) ends up in netlink_sendmsg and thus either netlink_broadcast and netlink_unicast, which is called directly as we have seen.
> -- > Dmitry
Evgeniy Polyakov
Only failure makes us experts. -- Theo de Raadt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |