linux-kernel - RE: [EXT] Re: [PATCH RFC net-next 06/19] net: mvpp2: increase BM pool size to 2048 buffers

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Date:   Sun, 10 Jan 2021 17:23:32 +0000
From:   Stefan Chulski <stefanc@...vell.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "thomas.petazzoni@...tlin.com" <thomas.petazzoni@...tlin.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Nadav Haklai <nadavh@...vell.com>,
        Yan Markman <ymarkman@...vell.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "mw@...ihalf.com" <mw@...ihalf.com>,
        "rmk+kernel@...linux.org.uk" <rmk+kernel@...linux.org.uk>,
        "atenart@...nel.org" <atenart@...nel.org>
Subject: RE: [EXT] Re: [PATCH RFC net-next  06/19] net: mvpp2: increase BM
 pool size to 2048 buffers

> External Email
> 
> ----------------------------------------------------------------------
> On Sun, Jan 10, 2021 at 05:30:10PM +0200, stefanc@...vell.com wrote:
> > From: Stefan Chulski <stefanc@...vell.com>
> >
> > BM pool size increased to support Firmware Flow Control.
> > Minimum depletion thresholds to support FC is 1024 buffers.
> > BM pool size increased to 2048 to have some 1024 buffers space between
> > depletion thresholds and BM pool size.
> >
> > Signed-off-by: Stefan Chulski <stefanc@...vell.com>
> > ---
> >  drivers/net/ethernet/marvell/mvpp2/mvpp2.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
> > b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
> > index 89b3ede..8dc669d 100644
> > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
> > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
> > @@ -851,8 +851,8 @@ enum mvpp22_ptp_packet_format {
> >  #define MVPP22_PTP_TIMESTAMPQUEUESELECT	BIT(18)
> >
> >  /* BM constants */
> > -#define MVPP2_BM_JUMBO_BUF_NUM		512
> > -#define MVPP2_BM_LONG_BUF_NUM		1024
> > +#define MVPP2_BM_JUMBO_BUF_NUM		2048
> > +#define MVPP2_BM_LONG_BUF_NUM		2048
> 
> Hi Stefan
> 
> Jumbo used to be 1/2 of regular. Do you know why?
> 
> It would be nice to have a comment in the commit message about why it is
> O.K. to change the ratio of jumbo to regular frames, and what if anything this
> does for memory requirements.
> 
> 	 Andrew

I don't know why it is half(no hardware restrictions for this). I would add to commit message new memory requirements for buffer allocations.

Thanks.