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From: Willy Tarreau <w@1wt•eu>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: davem@davemloft•net, netdev@vger•kernel.org,
	Thomas Petazzoni <thomas.petazzoni@free-electrons•com>,
	Gregory CLEMENT <gregory.clement@free-electrons•com>
Subject: Re: [PATCH 1/5] net: mvneta: increase the 64-bit rx/tx stats out of the hot path
Date: Mon, 13 Jan 2014 04:06:51 +0100	[thread overview]
Message-ID: <20140113030651.GB18330@1wt.eu> (raw)
In-Reply-To: <1389574192.31367.194.camel@edumazet-glaptop2.roam.corp.google.com>

On Sun, Jan 12, 2014 at 04:49:52PM -0800, Eric Dumazet wrote:
> On Sun, 2014-01-12 at 10:31 +0100, Willy Tarreau wrote:
> > Better count packets and bytes in the stack and on 32 bit then
> > accumulate them at the end for once. This saves two memory writes
> > and two memory barriers per packet. The incoming packet rate was
> > increased by 4.7% on the Openblocks AX3 thanks to this.
> > 
> > Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons•com>
> > Cc: Gregory CLEMENT <gregory.clement@free-electrons•com>
> > Signed-off-by: Willy Tarreau <w@1wt•eu>
> > ---
> >  drivers/net/ethernet/marvell/mvneta.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> 
> Reviewed-by: Eric Dumazet <edumazet@google•com>
> 
> Note that with such a cost, one has to wonder why we keep 64bit stats
> for this NIC on 32bit hosts...

At least this avoids wrapping if stats are not retrieved often enough.
As someone who had to support 32-bit stats in production on a firewall
running on kernel 2.4, I can say it really becomes a problem to graph
activity if stats are not collected as often as every 30 seconds, which
is short in certain environments.

Thanks,
Willy

  reply	other threads:[~2014-01-13  3:06 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-12  9:31 [PATCH 0/5] Assorted mvneta fixes Willy Tarreau
2014-01-12  9:31 ` [PATCH 1/5] net: mvneta: increase the 64-bit rx/tx stats out of the hot path Willy Tarreau
2014-01-13  0:49   ` Eric Dumazet
2014-01-13  3:06     ` Willy Tarreau [this message]
2014-01-12  9:31 ` [PATCH 2/5] net: mvneta: use per_cpu stats to fix an SMP lock up Willy Tarreau
2014-01-12 18:07   ` Eric Dumazet
2014-01-12 22:09     ` Willy Tarreau
2014-01-13  0:45       ` Eric Dumazet
2014-01-13  3:02         ` Willy Tarreau
2014-01-13  0:48   ` Eric Dumazet
2014-01-12  9:31 ` [PATCH 3/5] net: mvneta: do not schedule in mvneta_tx_timeout Willy Tarreau
2014-01-12 16:49   ` Ben Hutchings
2014-01-12 16:55     ` Willy Tarreau
2014-01-12 17:38       ` Ben Hutchings
2014-01-12 22:14         ` Willy Tarreau
2014-01-14 15:33         ` Willy Tarreau
2014-01-12  9:31 ` [PATCH 4/5] net: mvneta: add missing bit descriptions for interrupt masks and causes Willy Tarreau
2014-01-12  9:31 ` [PATCH 5/5] net: mvneta: replace Tx timer with a real interrupt Willy Tarreau
2014-01-13 23:22   ` Arnaud Ebalard
2014-01-14  7:30     ` Willy Tarreau
2014-01-12 19:21 ` [PATCH 0/5] Assorted mvneta fixes Arnaud Ebalard
2014-01-12 22:22   ` Willy Tarreau
2014-01-13 22:36     ` Arnaud Ebalard
2014-01-14  7:24       ` Willy Tarreau
2014-01-15  0:58 ` David Miller

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