From: "ezequiel.garcia@free-electrons•com" <ezequiel.garcia@free-electrons•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: "fugang.duan@freescale•com" <fugang.duan@freescale•com>,
David Laight <David.Laight@ACULAB•COM>,
"Frank.Li@freescale•com" <Frank.Li@freescale•com>,
"davem@davemloft•net" <davem@davemloft•net>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"shawn.guo@linaro•org" <shawn.guo@linaro•org>,
"bhutchings@solarflare•com" <bhutchings@solarflare•com>,
"stephen@networkplumber•org" <stephen@networkplumber•org>
Subject: Re: [PATCH v1 4/6] net: fec: Increase buffer descriptor entry number
Date: Fri, 30 May 2014 11:01:37 -0300 [thread overview]
Message-ID: <20140530140137.GC783@arch.cereza> (raw)
In-Reply-To: <1401455586.3645.96.camel@edumazet-glaptop2.roam.corp.google.com>
Hello Eric,
On 30 May 06:13 AM, Eric Dumazet wrote:
> On Fri, 2014-05-30 at 09:42 +0000, fugang.duan@freescale•com wrote:
> > From: David Laight <David.Laight@ACULAB•COM> Data: Friday, May 30, 2014 5:11 PM
> > >
> > >Does the driver support BQL (or similar) in order to limit the amount of
> > >queued tx traffic?
> > >Otherwise you've significantly increased the latency for connections other
> > >than one doing bulk tx.
> > >
> > > David
> > >
> > The driver still don't support BQL.
> > I will add the feature to support FEC. Thanks for your advise.
>
> Note that a full size TSO packet (44 or 45 MSS) requires about 88 or 90
> descriptors.
>
What's the rationale behing those numbers?
Following the Solarflare commit you pointed me a while ago, I've set
gso_max_segs to limit the number of descriptors in the mvneta and
mv643xx_eth drivers.
My understanding reading the sfc commit 7e6d06f0de3f7 is that the
maximum number of required descriptors would be around ~250:
/* Header and payload descriptor for each output segment, plus
* one for every input fragment boundary within a segment
*/
unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
Maybe I've misunderstood something?
PS: I was also about to add BQL support to the drivers...
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
next prev parent reply other threads:[~2014-05-30 14:05 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-30 2:05 [PATCH v1 0/6] *** net: fec: Enable Software TSO to improve the tx performance *** Fugang Duan
2014-05-30 2:05 ` [PATCH v1 1/6] net: fec: Factorize the .xmit transmit function Fugang Duan
2014-05-30 2:05 ` [PATCH v1 2/6] net: fec: Enable IP header hardware checksum Fugang Duan
2014-05-30 2:05 ` [PATCH v1 3/6] net: fec: Factorize feature setting Fugang Duan
2014-05-30 2:05 ` [PATCH v1 4/6] net: fec: Increase buffer descriptor entry number Fugang Duan
2014-05-30 9:10 ` David Laight
2014-05-30 9:42 ` fugang.duan
2014-05-30 13:13 ` Eric Dumazet
2014-05-30 14:01 ` ezequiel.garcia [this message]
2014-05-30 14:54 ` Eric Dumazet
2014-05-30 15:08 ` fugang.duan
2014-05-30 15:34 ` David Laight
2014-05-30 15:52 ` fugang.duan
2014-05-30 15:58 ` Eric Dumazet
2014-05-30 16:35 ` ezequiel.garcia
2014-05-30 15:40 ` Eric Dumazet
2014-05-30 15:46 ` fugang.duan
2014-05-30 2:05 ` [PATCH v1 5/6] net: fec: Add Scatter/gather support Fugang Duan
2014-05-30 4:37 ` Eric Dumazet
2014-05-30 4:48 ` fugang.duan
2014-05-30 14:26 ` Frank.Li
2014-05-30 2:05 ` [PATCH v1 6/6] net: fec: Add software TSO support Fugang Duan
2014-05-30 6:30 ` Eric Dumazet
2014-05-30 7:16 ` fugang.duan
2014-05-30 16:21 ` Eric Dumazet
2014-06-01 0:55 ` fugang.duan
2014-06-01 1:39 ` Eric Dumazet
2014-06-01 2:25 ` fugang.duan
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