[net-next,4/4] net: stmmac: Always use TX coalesce timer value when rescheduling
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Message ID 23c0ff1feddcc690ee66adebefdc3b10031afe1b.1576007149.git.Jose.Abreu@synopsys.com
State New
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Series
  • net: stmmac: Improvements for -next
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Commit Message

Jose Abreu Dec. 10, 2019, 7:54 p.m. UTC
When we have pending packets we re-arm the TX timer with a magic value.
Change this from the hardcoded value to the pre-defined TX coalesce
timer value.

Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>

---
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: netdev@vger.kernel.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jakub Kicinski Dec. 14, 2019, 8:28 p.m. UTC | #1
On Tue, 10 Dec 2019 20:54:44 +0100, Jose Abreu wrote:
> When we have pending packets we re-arm the TX timer with a magic value.
> Change this from the hardcoded value to the pre-defined TX coalesce
> timer value.

s/pre-defined/user controlled/ ?

> Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
> ---
> Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>
> Cc: Jose Abreu <joabreu@synopsys.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: netdev@vger.kernel.org
> Cc: linux-stm32@st-md-mailman.stormreply.com
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index f61780ae30ac..726a17d9cc35 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1975,7 +1975,7 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
>  
>  	/* We still have pending packets, let's call for a new scheduling */
>  	if (tx_q->dirty_tx != tx_q->cur_tx)
> -		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(10));
> +		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer));

I think intent of this code is to re-check the ring soon. The same
value of 10 is used in stmmac_tx_timer() for quick re-check.

tx_coal_timer defaults to 1000, so it's quite a jump from 10 to 1000.

I think the commit message leaves too much unsaid.

Also if you want to change to the ethtool timeout value, could you move 
stmmac_tx_timer_arm() and reuse that helper?

>  
>  	__netif_tx_unlock_bh(netdev_get_tx_queue(priv->dev, queue));
>
Jose Abreu Dec. 16, 2019, 9:20 a.m. UTC | #2
From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Dec/14/2019, 20:28:37 (UTC+00:00)

> On Tue, 10 Dec 2019 20:54:44 +0100, Jose Abreu wrote:
> > When we have pending packets we re-arm the TX timer with a magic value.
> > Change this from the hardcoded value to the pre-defined TX coalesce
> > timer value.
> 
> s/pre-defined/user controlled/ ?
> 
> > Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
> > ---
> > Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
> > Cc: Alexandre Torgue <alexandre.torgue@st.com>
> > Cc: Jose Abreu <joabreu@synopsys.com>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> > Cc: netdev@vger.kernel.org
> > Cc: linux-stm32@st-md-mailman.stormreply.com
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-kernel@vger.kernel.org
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > index f61780ae30ac..726a17d9cc35 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > @@ -1975,7 +1975,7 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
> >  
> >  	/* We still have pending packets, let's call for a new scheduling */
> >  	if (tx_q->dirty_tx != tx_q->cur_tx)
> > -		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(10));
> > +		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer));
> 
> I think intent of this code is to re-check the ring soon. The same
> value of 10 is used in stmmac_tx_timer() for quick re-check.
> 
> tx_coal_timer defaults to 1000, so it's quite a jump from 10 to 1000.
> 
> I think the commit message leaves too much unsaid.
> 
> Also if you want to change to the ethtool timeout value, could you move 
> stmmac_tx_timer_arm() and reuse that helper?

Yeah, it's a quick re-check but 10us can be too low on some speeds and 
leads to CPU useless-looping. The intent is to let this always be 
configurable by user.

---
Thanks,
Jose Miguel Abreu
Jakub Kicinski Dec. 16, 2019, 8:16 p.m. UTC | #3
On Mon, 16 Dec 2019 09:20:53 +0000, Jose Abreu wrote:
> > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > index f61780ae30ac..726a17d9cc35 100644
> > > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > @@ -1975,7 +1975,7 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
> > >  
> > >  	/* We still have pending packets, let's call for a new scheduling */
> > >  	if (tx_q->dirty_tx != tx_q->cur_tx)
> > > -		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(10));
> > > +		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer));  
> > 
> > I think intent of this code is to re-check the ring soon. The same
> > value of 10 is used in stmmac_tx_timer() for quick re-check.
> > 
> > tx_coal_timer defaults to 1000, so it's quite a jump from 10 to 1000.
> > 
> > I think the commit message leaves too much unsaid.
> > 
> > Also if you want to change to the ethtool timeout value, could you move 
> > stmmac_tx_timer_arm() and reuse that helper?  
> 
> Yeah, it's a quick re-check but 10us can be too low on some speeds and 
> leads to CPU useless-looping. The intent is to let this always be 
> configurable by user.

Okay, please do mention the bump from 10us to the default of 1ms in the
commit message, though.

Patch
diff mbox series

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f61780ae30ac..726a17d9cc35 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1975,7 +1975,7 @@  static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
 
 	/* We still have pending packets, let's call for a new scheduling */
 	if (tx_q->dirty_tx != tx_q->cur_tx)
-		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(10));
+		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer));
 
 	__netif_tx_unlock_bh(netdev_get_tx_queue(priv->dev, queue));