From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eilon Greenstein" Subject: Re: [RFC net-next 05/14] Fix intel/ixgbevf Date: Tue, 19 Jun 2012 21:24:28 +0300 Message-ID: <1340130268.2486.19.camel@lb-tlvb-eilong.il.broadcom.com> References: <1340118848-30978-1-git-send-email-yuvalmin@broadcom.com> <1340118848-30978-6-git-send-email-yuvalmin@broadcom.com> <4FE09D3F.4060305@intel.com> <1340122013.2486.14.camel@lb-tlvb-eilong.il.broadcom.com> <20120619110704.000045b2@unknown> Reply-To: eilong@broadcom.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "Alexander Duyck" , "Yuval Mintz" , netdev@vger.kernel.org, davem@davemloft.net, "Jeff Kirsher" To: "Greg Rose" Return-path: Received: from mms3.broadcom.com ([216.31.210.19]:3231 "EHLO mms3.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751549Ab2FSSYq (ORCPT ); Tue, 19 Jun 2012 14:24:46 -0400 In-Reply-To: <20120619110704.000045b2@unknown> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2012-06-19 at 11:07 -0700, Greg Rose wrote: > On Tue, 19 Jun 2012 19:06:53 +0300 > Eilon Greenstein wrote: > > > On Tue, 2012-06-19 at 08:39 -0700, Alexander Duyck wrote: > > > On 06/19/2012 08:13 AM, Yuval Mintz wrote: > > > > Signed-off-by: Yuval Mintz > > > > Signed-off-by: Eilon Greenstein > > > > > > > > Cc: Jeff Kirsher > > > > --- > > > > drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 5 +++-- > > > > 1 files changed, 3 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c > > > > b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c index > > > > f69ec42..3ad46c2 100644 --- > > > > a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c +++ > > > > b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c @@ -2014,7 > > > > +2014,7 @@ err_tx_ring_allocation: static int > > > > ixgbevf_set_interrupt_capability(struct ixgbevf_adapter *adapter) > > > > { int err = 0; > > > > - int vector, v_budget; > > > > + int vector, v_budget, ncpu; > > > > > > > > /* > > > > * It's easy to be greedy for MSI-X vectors, but it > > > > really @@ -2022,8 +2022,9 @@ static int > > > > ixgbevf_set_interrupt_capability(struct ixgbevf_adapter *adapter) > > > > * than CPU's. So let's be conservative and only ask for > > > > * (roughly) twice the number of vectors as there are > > > > CPU's. */ > > > > + ncpu = min_t(int, num_online_cpus(), > > > > DEFAULT_MAX_NUM_RSS_QUEUES); v_budget = > > > > min(adapter->num_rx_queues + adapter->num_tx_queues, > > > > - (int)(num_online_cpus() * 2)) + > > > > NON_Q_VECTORS; > > > > + ncpu * 2) + NON_Q_VECTORS; > > > > > > > > /* A failure in MSI-X entry allocation isn't fatal, but > > > > it does > > > > * mean we disable MSI-X capabilities of the adapter. */ > > > This change is pointless on the ixgbevf driver. The VF hardware can > > > support at most 4 RSS queues. As such num_rx_queues + num_tx_queues > > > will never exceed 8 so you are essentially adding a necessary > > > min(x,8). > > > > It is pointless with the current value, but if someone will edit the > > kernel source code and replace the 8 with a 2, it will become > > meaningful. The compiler will optimize this part, and I think that for > > completion, it is best to keep this reference so a future default > > number change will not be missed. > > > > Eilon > > I don't feel there is any real point to making this change to the > ixgbevf driver. 82599 virtual functions have 3 MSI-X vectors, one of > which is for the mailbox and the other two can be shared with tx/rx > queue pairs or assigned separately to tx or rx queues. So this code is > pointless no matter what value is set for DEFAULT_MAX_NUM_RSS_QUEUES. > Perhaps the patches to the other drivers in your RFC will have some > effect but this one looks like a no-op for the ixgbevf driver so there > is no reason for it. OK - I guess we can just add a comment in this location saying that using DEFAULT_MAX_NUM_RSS_QUEUES is meaningless for the ixgbevf with that explanation so it will not look as if it was simply over looked. Thanks, Eilon