linux-kernel - Re: linux-next network throughput performance regression

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Message-ID: <1446925821.17135.24.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Sat, 07 Nov 2015 11:50:21 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Ahern <dsa@...ulusnetworks.com>
Cc:	Simon Xiao <sixiao@...rosoft.com>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	KY Srinivasan <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: Re: linux-next network throughput performance regression

On Sat, 2015-11-07 at 11:35 -0800, Eric Dumazet wrote:
> On Fri, 2015-11-06 at 14:30 -0700, David Ahern wrote:
> > On 11/6/15 2:18 PM, Simon Xiao wrote:
> > > The .config file used to build linux-next kernel is attached to this mail.
> > 
> > Thanks.
> > 
> > Failed to notice this on the first response; my brain filled in. Why 
> > linux-next tree? Can you try net-next which is more relevant for this 
> > mailing list, post the top commit id and config file used?
> 
> Throughput on a single TCP flow for a 40G NIC can be tricky to tune.
> 
> Make sure IRQ are properly setup/balanced, as I know that IRQ names were
> changed recently and your scripts might have not noticed...
> 
> Also "ethtool -c eth0" might show very different interrupt coalescing
> params ?
> 
> I too have a Mellanox 40Gb in my lab and saw no difference in
> performance with recent kernels.
> 
> Of course, a simple "perf record -a -g sleep 4 ; perf report" might
> point to some obvious issue. Like unexpected segmentation in case of
> forwarding...
> 
> 

I did a test with current net tree on both sender and receiver

lpaa23:~# ./netperf -H 10.246.7.152
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
10.246.7.152 () port 0 AF_INET
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

 87380  16384  16384    10.00    26864.98   
lpaa23:~# ethtool -c eth1
Coalesce parameters for eth1:
Adaptive RX: on  TX: off
stats-block-usecs: 0
sample-interval: 0
pkt-rate-low: 400000
pkt-rate-high: 450000

rx-usecs: 16
rx-frames: 44
rx-usecs-irq: 0
rx-frames-irq: 0

tx-usecs: 16
tx-frames: 16
tx-usecs-irq: 0
tx-frames-irq: 256

rx-usecs-low: 0
rx-frame-low: 0
tx-usecs-low: 0
tx-frame-low: 0

rx-usecs-high: 128
rx-frame-high: 0
tx-usecs-high: 0
tx-frame-high: 0

lpaa23:~# ethtool -C eth1 tx-usecs 4 tx-frames 4
lpaa23:~# ./netperf -H 10.246.7.152
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
10.246.7.152 () port 0 AF_INET
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

 87380  16384  16384    10.00    30206.27   


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