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Date: Mon, 25 Aug 2008 07:57:44 +0000 From: Jarek Poplawski <jarkao2@...il.com> To: David Miller <davem@...emloft.net> Cc: hadi@...erus.ca, alexander.duyck@...il.com, jeffrey.t.kirsher@...el.com, jeff@...zik.org, netdev@...r.kernel.org, alexander.h.duyck@...el.com Subject: Re: [PATCH 3/3] pkt_sched: restore multiqueue prio scheduler On Mon, Aug 25, 2008 at 12:48:25AM -0700, David Miller wrote: > From: Jarek Poplawski <jarkao2@...il.com> > Date: Mon, 25 Aug 2008 06:06:40 +0000 > > > It seems the priority can really be misleading here. Do you mean these > > hwqueues are internally prioritized too? This would be strange to me, > > because why would we need this independent locking per hwqueue if > > everything has to wait for the most prioritized hwqueue anyway? And, > > if so, current dev_pick_tx() with simple_tx_hash() would always harm > > some flows directing them to lower priority hwqueues?! > > Yes some can do internal prioritization in hardware. > > But even if not, this means even if the card does flow based > multiqueue, this is still the right thing to do. > > Think about what actually happens on the wire as a result of > our actions, rather than intuition :-) > > > But, even if it's true, let's take a look at fifo: a packet at the > > head of the qdisc's queue could be hashed to the last hwqueue. If > > it's stopped for some reason, this packed would be constantly > > requeued blocking all other packets, while their hwqueues are ready > > and empty! > > If we feed packets after the first one to the card, we would not > be implementing a FIFO. Not necessarilly so: if separate flows are hashed to "their" hwqueues, a FIFO per flow would be still obeyed. Jarek P. -- 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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