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Re: Re: [PATCH v3 5/6] mwifiex: do not aggregate tcp ack in usb tx aggregation queue

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Hi Brain,

> -----Original Message-----
> From: Brian Norris [mailto:briannorris@xxxxxxxxxxxx]
> Sent: 2017年5月20日 0:43
> To: Xinming Hu
> Cc: Linux Wireless; Kalle Valo; Dmitry Torokhov; rajatja@xxxxxxxxxx; Zhiyuan
> Yang; Cathy Luo; Xinming Hu; Ganapathi Bhat
> Subject: [EXT] Re: [PATCH v3 5/6] mwifiex: do not aggregate tcp ack in usb tx
> aggregation queue
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Fri, May 19, 2017 at 09:06:44AM +0000, Xinming Hu wrote:
> > From: Xinming Hu <huxm@xxxxxxxxxxx>
> >
> > Tcp ack should be send as soon to avoid throuput drop during receive
> > tcp traffic.
> >
> > Signed-off-by: Xinming Hu <huxm@xxxxxxxxxxx>
> > Signed-off-by: Cathy Luo <cluo@xxxxxxxxxxx>
> > Signed-off-by: Ganapathi Bhat <gbhat@xxxxxxxxxxx>
> > ---
> > v2: same as v1
> > v3: avoid to use magic tcp flag (Kalle)
> > ---
> >  drivers/net/wireless/marvell/mwifiex/11n_aggr.c |  4 ++++
> >  drivers/net/wireless/marvell/mwifiex/decl.h     |  1 +
> >  drivers/net/wireless/marvell/mwifiex/main.c     | 26
> +++++++++++++++++++++++++
> >  drivers/net/wireless/marvell/mwifiex/main.h     |  1 +
> >  drivers/net/wireless/marvell/mwifiex/usb.c      |  6 ++++--
> >  5 files changed, 36 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/marvell/mwifiex/11n_aggr.c
> > b/drivers/net/wireless/marvell/mwifiex/11n_aggr.c
> > index e8ffb26..cbf3bc2 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/11n_aggr.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/11n_aggr.c
> > @@ -194,6 +194,10 @@
> >
> >  	if (tx_info_src->flags & MWIFIEX_BUF_FLAG_TDLS_PKT)
> >  		tx_info_aggr->flags |= MWIFIEX_BUF_FLAG_TDLS_PKT;
> > +
> > +	if (tx_info_src->flags & MWIFIEX_BUF_FLAG_TCP_ACK)
> > +		tx_info_aggr->flags |= MWIFIEX_BUF_FLAG_TCP_ACK;
> > +
> >  	tx_info_aggr->flags |= MWIFIEX_BUF_FLAG_AGGR_PKT;
> >  	skb_aggr->priority = skb_src->priority;
> >  	skb_aggr->tstamp = skb_src->tstamp;
> > diff --git a/drivers/net/wireless/marvell/mwifiex/decl.h
> > b/drivers/net/wireless/marvell/mwifiex/decl.h
> > index 188e4c3..0487420 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/decl.h
> > +++ b/drivers/net/wireless/marvell/mwifiex/decl.h
> > @@ -89,6 +89,7 @@
> >  #define MWIFIEX_BUF_FLAG_EAPOL_TX_STATUS   BIT(3)
> >  #define MWIFIEX_BUF_FLAG_ACTION_TX_STATUS  BIT(4)
> >  #define MWIFIEX_BUF_FLAG_AGGR_PKT          BIT(5)
> > +#define MWIFIEX_BUF_FLAG_TCP_ACK           BIT(6)
> >
> >  #define MWIFIEX_BRIDGED_PKTS_THR_HIGH      1024
> >  #define MWIFIEX_BRIDGED_PKTS_THR_LOW        128
> > diff --git a/drivers/net/wireless/marvell/mwifiex/main.c
> > b/drivers/net/wireless/marvell/mwifiex/main.c
> > index 2c42191..b7d835c 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/main.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/main.c
> > @@ -851,6 +851,30 @@ struct sk_buff *
> >  	return skb;
> >  }
> >
> > +static bool is_piggyback_tcp_ack(struct sk_buff *skb) {
> > +	struct ethhdr *ethh = NULL;
> > +	struct iphdr  *iph = NULL;
> > +	struct tcphdr *tcph = NULL;
> > +
> > +	ethh = (struct ethhdr *)skb->data;
> > +	if (ntohs(ethh->h_proto) != ETH_P_IP)
> > +		return false;
> 
> What about IPv6?
> 
> Also, what about all the protocols that you're *not* hacking this for?
> Is the latency induced by aggregation really that poor?
> 
> I'm not really a networking expert here, but this whole patch smells bad to me.
> 


We didn't observe throughput drop due to ack block yet..
It was considered to be an optional enhance.
Let's drop it in this patch serials.

Regards,
Simon
> > +
> > +	iph = (struct iphdr *)((u8 *)ethh + sizeof(struct ethhdr));
> > +	if (iph->protocol != IPPROTO_TCP)
> > +		return false;
> > +
> > +	tcph = (struct tcphdr *)((u8 *)iph + iph->ihl * 4);
> > +	/* Piggyback ack without payload*/
> > +	if (tcp_flag_word(tcph) == TCP_FLAG_ACK &&
> > +	    ntohs(iph->tot_len) <= (iph->ihl + tcph->doff) * 4) {
> > +		return true;
> > +	}
> > +
> > +	return false;
> > +}
> > +
> >  /*
> >   * CFG802.11 network device handler for data transmission.
> >   */
> > @@ -904,6 +928,8 @@ struct sk_buff *
> >  	tx_info->bss_num = priv->bss_num;
> >  	tx_info->bss_type = priv->bss_type;
> >  	tx_info->pkt_len = skb->len;
> > +	if (is_piggyback_tcp_ack(skb))
> > +		tx_info->flags |= MWIFIEX_BUF_FLAG_TCP_ACK;
> >
> >  	multicast = is_multicast_ether_addr(skb->data);
> >
> > diff --git a/drivers/net/wireless/marvell/mwifiex/main.h
> > b/drivers/net/wireless/marvell/mwifiex/main.h
> > index 1f7e6c3..b0010a9 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/main.h
> > +++ b/drivers/net/wireless/marvell/mwifiex/main.h
> > @@ -49,6 +49,7 @@
> >  #include <linux/pm_runtime.h>
> >  #include <linux/slab.h>
> >  #include <linux/of_irq.h>
> > +#include <linux/tcp.h>
> 
> I dislike polluting the (driver-global) main.h with #include's that only are used
> in one file. Especially when you talk about seemingly layer-violating TCP hacks.
> Can you move this to main.c instead?
> 
> Brian
> 
> >
> >  #include "decl.h"
> >  #include "ioctl.h"
> > diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c
> > b/drivers/net/wireless/marvell/mwifiex/usb.c
> > index f230017..e9c3d43 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/usb.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/usb.c
> > @@ -934,6 +934,7 @@ static int mwifiex_usb_aggr_tx_data(struct
> mwifiex_adapter *adapter, u8 ep,
> >  	struct urb_context *context = NULL;
> >  	struct txpd *local_tx_pd =
> >  		(struct txpd *)((u8 *)skb->data + adapter->intf_hdr_len);
> > +	struct mwifiex_txinfo *tx_info = MWIFIEX_SKB_TXCB(skb);
> >  	u8 f_send_aggr_buf = 0;
> >  	u8 f_send_cur_buf = 0;
> >  	u8 f_precopy_cur_buf = 0;
> > @@ -989,8 +990,9 @@ static int mwifiex_usb_aggr_tx_data(struct
> mwifiex_adapter *adapter, u8 ep,
> >  		}
> >  	}
> >
> > -	if (local_tx_pd->flags & MWIFIEX_TxPD_POWER_MGMT_NULL_PACKET) {
> > -		/* Send NULL packet immediately*/
> > +	if (local_tx_pd->flags & MWIFIEX_TxPD_POWER_MGMT_NULL_PACKET ||
> > +	    tx_info->flags & MWIFIEX_BUF_FLAG_TCP_ACK) {
> > +		/* Send NULL data/TCP ACK packet immediately*/
> >  		if (f_precopy_cur_buf) {
> >  			if (skb_queue_empty(&port->tx_aggr.aggr_list)) {
> >  				f_precopy_cur_buf = 0;
> > --
> > 1.9.1
> >




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