From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v2 net] r8169: fix NAPI handling under high load Date: Thu, 18 Oct 2018 11:02:02 -0700 Message-ID: <05eb4233-bf98-4aeb-73f6-94fec46ca3de@gmail.com> References: <8d75498e-6f43-a699-3a0a-fb4a2b5dc860@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" To: Heiner Kallweit , David Miller , Realtek linux nic maintainers Return-path: Received: from mail-pf1-f193.google.com ([209.85.210.193]:46822 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729681AbeJSCEL (ORCPT ); Thu, 18 Oct 2018 22:04:11 -0400 Received: by mail-pf1-f193.google.com with SMTP id r64-v6so15221649pfb.13 for ; Thu, 18 Oct 2018 11:02:04 -0700 (PDT) In-Reply-To: <8d75498e-6f43-a699-3a0a-fb4a2b5dc860@gmail.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 10/18/2018 10:56 AM, Heiner Kallweit wrote: > rtl_rx() and rtl_tx() are called only if the respective bits are set > in the interrupt status register. Under high load NAPI may not be > able to process all data (work_done == budget) and it will schedule > subsequent calls to the poll callback. > rtl_ack_events() however resets the bits in the interrupt status > register, therefore subsequent calls to rtl8169_poll() won't call > rtl_rx() and rtl_tx() - chip interrupts are still disabled. > > Fix this by calling rtl_rx() and rtl_tx() independent of the bits > set in the interrupt status register. Both functions will detect > if there's nothing to do for them. > > Fixes: da78dbff2e05 ("r8169: remove work from irq handler.") > Signed-off-by: Heiner Kallweit > --- > v2: > - added "Fixes" tag > --- > drivers/net/ethernet/realtek/r8169.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c > index 8c4f49adc..7caf3b7e9 100644 > --- a/drivers/net/ethernet/realtek/r8169.c > +++ b/drivers/net/ethernet/realtek/r8169.c > @@ -6528,17 +6528,15 @@ static int rtl8169_poll(struct napi_struct *napi, int budget) > struct rtl8169_private *tp = container_of(napi, struct rtl8169_private, napi); > struct net_device *dev = tp->dev; > u16 enable_mask = RTL_EVENT_NAPI | tp->event_slow; > - int work_done= 0; > + int work_done; > u16 status; > > status = rtl_get_events(tp); > rtl_ack_events(tp, status & ~tp->event_slow); > > - if (status & RTL_EVENT_NAPI_RX) > - work_done = rtl_rx(dev, tp, (u32) budget); > + work_done = rtl_rx(dev, tp, (u32) budget); > > - if (status & RTL_EVENT_NAPI_TX) > - rtl_tx(dev, tp); > + rtl_tx(dev, tp); > > if (status & tp->event_slow) { > enable_mask &= ~tp->event_slow; > One has to wonder why rtl8169_poll(), which might be called in a loop under DOS, has to call rtl_ack_events() ? Should not this be called one time from hard irq handler instead ?