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Message-ID: <1286377633.2371.11.camel@achroite.uk.solarflarecom.com> Date: Wed, 06 Oct 2010 16:07:13 +0100 From: Ben Hutchings <bhutchings@...arflare.com> To: John Fastabend <john.r.fastabend@...el.com> Cc: Eric Dumazet <eric.dumazet@...il.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "therbert@...gle.com" <therbert@...gle.com> Subject: Re: [net-next-2.6 PATCH] net: netif_set_real_num_rx_queues may cap num_rx_queues at init time On Wed, 2010-10-06 at 07:52 -0700, John Fastabend wrote: > On 10/5/2010 10:45 AM, John Fastabend wrote: > > On 10/5/2010 9:34 AM, Ben Hutchings wrote: > >> On Tue, 2010-10-05 at 09:08 -0700, John Fastabend wrote: > >>> On 10/4/2010 10:35 PM, Eric Dumazet wrote: [...] > >>>> Why should we keep num_rx_queues > real_num_rx_queues ? > >>>> > >>> > >>> If we do not ever need them then we should not keep them I agree. > >>> But having netif_set_real_num_rx_queues set something other then > >>> 'real_num_rx_queues' does not seem right to me at least. Also > >>> netif_set_real_num_tx_queues and netif_set_real_num_rx_queues have > >>> different behavior. It would be nice if this weren't the case but > >>> they allocate queues in two places. > >> [...] > >> > >> I only did this to satisfy Eric's desire to reduce memory usage. > >> However, I believe that there are currently no drivers that dynamically > >> increase numbers of RX or TX queues. Until there are, there is not much > >> point in removing this assignment to num_rx_queues. > >> > >> Ben. > >> > > > > ixgbe increases the real_num_[rx|tx]_queues when FCoE or DCB is enabled. > > Also many of the drivers could increase the number of queues if they were > > given more interrupt vectors at some point. > > > If I update the handful drivers that use netif_set_real_num_rx_queues() > before the netdevice is registered to explicitly set num_rx_queues this > would address Eric's concerns and fix drivers that really only want to set > real_num_rx_queue. > > Any thoughts? Don't add assignments to num_rx_queues. If it's useful to increase the number of RX queues later then just remove the assignment to num_rx_queues from netif_set_real_num_rx_queues() and be done with it. The waste of memory is minimal now that we only allocate kobjects for real_num_rx_queues. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. -- 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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