linux-kernel - RE: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing support for different IPv4 IHL values

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Message-ID: <CO6PR18MB3873F606BAA003DF8F0DA5D7B04F9@CO6PR18MB3873.namprd18.prod.outlook.com>
Date:   Tue, 13 Apr 2021 10:03:51 +0000
From:   Stefan Chulski <stefanc@...vell.com>
To:     Marcin Wojtas <mw@...ihalf.com>
CC:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        "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>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "atenart@...nel.org" <atenart@...nel.org>,
        Liron Himi <lironh@...vell.com>, Dana Vardi <danat@...vell.com>
Subject: RE: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing support for
 different IPv4 IHL values



> -----Original Message-----
> From: Marcin Wojtas <mw@...ihalf.com>
> Sent: Tuesday, April 13, 2021 12:59 PM
> To: Stefan Chulski <stefanc@...vell.com>
> Cc: Russell King - ARM Linux admin <linux@...linux.org.uk>;
> netdev@...r.kernel.org; thomas.petazzoni@...tlin.com;
> davem@...emloft.net; Nadav Haklai <nadavh@...vell.com>; Yan
> Markman <ymarkman@...vell.com>; linux-kernel@...r.kernel.org;
> kuba@...nel.org; andrew@...n.ch; atenart@...nel.org; Liron Himi
> <lironh@...vell.com>; Dana Vardi <danat@...vell.com>
> Subject: Re: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing support for
> different IPv4 IHL values
> 
> Hi Stefan,
> 
> wt., 13 kwi 2021 o 11:56 Stefan Chulski <stefanc@...vell.com> napisał(a):
> >
> > > > -----Original Message-----
> > > > From: Russell King - ARM Linux admin <linux@...linux.org.uk>
> > > > Sent: Tuesday, April 13, 2021 12:18 PM
> > > > To: Stefan Chulski <stefanc@...vell.com>
> > > > Cc: netdev@...r.kernel.org; thomas.petazzoni@...tlin.com;
> > > > davem@...emloft.net; Nadav Haklai <nadavh@...vell.com>; Yan
> > > Markman
> > > > <ymarkman@...vell.com>; linux-kernel@...r.kernel.org;
> > > kuba@...nel.org;
> > > > mw@...ihalf.com; andrew@...n.ch; atenart@...nel.org; Liron Himi
> > > > <lironh@...vell.com>; Dana Vardi <danat@...vell.com>
> > > > Subject: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing
> > > > support for different IPv4 IHL values
> > > >
> > > > External Email
> > > >
> > > > ------------------------------------------------------------------
> > > > ---- On Tue, Apr 13, 2021 at 11:45:31AM +0300, stefanc@...vell.com
> > > > wrote:
> > > > > From: Stefan Chulski <stefanc@...vell.com>
> > > > >
> > > > > Add parser entries for different IPv4 IHL values.
> > > > > Each entry will set the L4 header offset according to the IPv4 IHL field.
> > > > > L3 header offset will set during the parsing of the IPv4 protocol.
> > > >
> > > > What is the impact of this commit? Is something broken at the
> > > > moment, if so what? Does this need to be backported to stable
> kernels?
> > > >
> > > > These are key questions, of which the former two should be covered
> > > > in every commit message so that the reason for the change can be
> known.
> > > > It's no good just describing what is being changed in the commit
> > > > without also describing why the change is being made.
> > > >
> > > > Thanks.
> > >
> > > Due to missed parser support for IP header length > 20, RX IPv4
> > > checksum offload fail.
> > >
> > > Regards.
> >
> > Currently driver set skb->ip_summed = CHECKSUM_NONE and checksum
> done by software.
> > So this just improve performance for packets with IP header length > 20.
> > IMO we can keep it in net-next.
> >
> > Stefan.
> 
> Please update the commit message in v2 with the explanation.
> 
> Also - is there an easy way to test it? L3 forwarding with forced header
> length?
> 
> Thanks,
> Marcin

I will wait for additional comments and resend it tomorrow.
We probably should see this in "perf top" in L3 forwarding. Less cycles consumed by Network stack checksum callback.

Regards.