netdev - Re: [PATCH net-next 2/3] net: mvpp2: adjust gso stop wake thresholds

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Date:   Tue, 27 Feb 2018 18:13:52 +0100
From:   Antoine Tenart <antoine.tenart@...tlin.com>
To:     David Miller <davem@...emloft.net>
Cc:     antoine.tenart@...tlin.com, ymarkman@...vell.com, mw@...ihalf.com,
        stefanc@...vell.com, thomas.petazzoni@...e-electrons.com,
        gregory.clement@...e-electrons.com,
        miquel.raynal@...e-electrons.com, nadavh@...vell.com,
        maxime.chevallier@...tlin.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 2/3] net: mvpp2: adjust gso stop wake thresholds

Hi David,

On Tue, Feb 27, 2018 at 11:13:06AM -0500, David Miller wrote:
> From: Antoine Tenart <antoine.tenart@...tlin.com>
> > From: Yan Markman <ymarkman@...vell.com>
> > -#define MVPP2_MAX_TSO_SEGS		300
> > +#define MVPP2_MAX_TSO_SEGS		100
> >  #define MVPP2_MAX_SKB_DESCS		(MVPP2_MAX_TSO_SEGS * 2 + MAX_SKB_FRAGS)
> >  
> >  /* Dfault number of RXQs in use */
> > @@ -5810,7 +5810,7 @@ static int mvpp2_txq_init(struct mvpp2_port *port,
> >  		txq_pcpu->tso_headers = NULL;
> >  
> >  		txq_pcpu->stop_threshold = txq->size - MVPP2_MAX_SKB_DESCS;
> > -		txq_pcpu->wake_threshold = txq_pcpu->stop_threshold / 2;
> > +		txq_pcpu->wake_threshold = txq_pcpu->stop_threshold - 100;
> >  
> 
> This number 100 is a magic constant.  If it is related to
> MVPP2_MAX_TSO_SEGS, please use that define.  Otherwise
> define a new one which is descriptive.

I agree. I'll ask Yan about it and update if possible.

Thanks!
Antoine

-- 
Antoine Ténart, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com