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Date: Tue, 17 Jun 2008 14:40:41 -0700 (PDT) From: David Miller <davem@...emloft.net> To: pmullaney@...ell.com Cc: herbert@...dor.apana.org.au, GHaskins.WAL-1.WALTHAM@...ell.com, chuck.lever@...cle.com, netdev@...r.kernel.org Subject: Re: Killing sk->sk_callback_lock From: "Patrick Mullaney" <pmullaney@...ell.com> Date: Tue, 17 Jun 2008 07:38:29 -0600 > >>> On Mon, Jun 16, 2008 at 9:53 PM, in message > <20080616.185328.85842051.davem@...emloft.net>, David Miller > <davem@...emloft.net> wrote: > > Once the task is woken up the first time, future calls to > > these callback functions should do nothing other than take > > the sk_callback_lock and test some state. > > > > Since the task is awake already, wakeups should be bypassed > > or at worst be a nop. > > The task can go directly back into a wait. This will effectively yield 2 > wake ups per udp request-response. I made the mistake of assuming that a high performance threaded networking application would use non-blocking operations and select/poll/epoll, which is clearly not the case here. It's blocking in a recv() and this is woken up by a write space extraneous wakeup. It does need to be fixed and I'll look at the most recent patch submission and also try to imagine some other ideas. Herbert mentioned creating a seperate wait queue for write space wakeups. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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