Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:51469 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964844Ab3BTQVK (ORCPT ); Wed, 20 Feb 2013 11:21:10 -0500 Message-ID: <1361377243.8629.34.camel@jlt4.sipsolutions.net> (sfid-20130220_172115_814717_D2D0C868) Subject: Re: 3.7.8/amd64 full interrupt hangs due to iwlwifi under big nfs copies out From: Johannes Berg To: Eric Dumazet Cc: Marc MERLIN , David Miller , Larry.Finger@lwfinger.net, bhutchings@solarflare.com, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Date: Wed, 20 Feb 2013 17:20:43 +0100 In-Reply-To: <1361373064.19353.180.camel@edumazet-glaptop> (sfid-20130220_161110_395796_DBAC0744) References: <1333998672.3007.245.camel@edumazet-glaptop> <20120409.153452.1284163346306246866.davem@davemloft.net> <1334030180.13293.98.camel@edumazet-glaptop> <20120410051127.GA32048@merlins.org> <1334038263.2907.1.camel@edumazet-glaptop> <20120411052733.GA17352@merlins.org> <20120715215935.GF24420@merlins.org> <1342419529.3265.12217.camel@edumazet-glaptop> <20120716151826.GA10586@merlins.org> <1342455717.2830.14.camel@edumazet-glaptop> <20130219040557.GB4778@merlins.org> <1361251033.19353.120.camel@edumazet-glaptop> (sfid-20130219_061917_530878_1ED7A14C) <1361268221.8553.1.camel@jlt4.sipsolutions.net> <1361290909.19353.140.camel@edumazet-glaptop> (sfid-20130219_172155_748777_C3ED0F5E) <1361351538.8629.3.camel@jlt4.sipsolutions.net> (sfid-20130220_101252_930264_DBD3955C) <1361351703.8629.5.camel@jlt4.sipsolutions.net> <1361373064.19353.180.camel@edumazet-glaptop> (sfid-20130220_161110_395796_DBAC0744) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, 2013-02-20 at 07:11 -0800, Eric Dumazet wrote: > On Wed, 2013-02-20 at 10:15 +0100, Johannes Berg wrote: > > > OTOH, this affects the protocol, and when you really can't allocate any > > order-1 pages you pointed out yourself that many other things also won't > > work, so I'm not really sure it makes a big difference if we change the > > driver? > > It will make a huge difference, even on non pressure mode, as TCP > receive window will grow twice faster. Hmm, why does that depend on the allocation size? > Unless wifi speed reaches 10Gbps, following patch should do the trick > > > diff --git a/drivers/net/wireless/iwlwifi/dvm/rx.c b/drivers/net/wireless/iwlwifi/dvm/rx.c > index a4eed20..77a3ee3 100644 > --- a/drivers/net/wireless/iwlwifi/dvm/rx.c > +++ b/drivers/net/wireless/iwlwifi/dvm/rx.c > @@ -750,7 +750,12 @@ static void iwlagn_pass_packet_to_mac80211(struct iwl_priv *priv, > /* Dont use dev_alloc_skb(), we'll have enough headroom once > * ieee80211_hdr pulled. > */ > - skb = alloc_skb(128, GFP_ATOMIC); > + fraglen = 128; > + /* if we use order-1 pages, copy to get better TCP performance */ > + if (rxb->truesize > PAGE_SIZE) > + fraglen = max_t(unsigned, fraglen, len); > + > + skb = alloc_skb(fraglen, GFP_ATOMIC); Hmm, I don't quite understand -- that's not doing any copy? FWIW if you do the copy you should not "steal" the pages, then they'd be recycled in the RX ring right away. johannes