From: Eric Dumazet <dada1@cosmosbay•com>
To: Andrew Gallatin <gallatin@myri•com>
Cc: Herbert Xu <herbert@gondor•apana.org.au>,
David Miller <davem@davemloft•net>,
brice@myri•com, sgruszka@redhat•com, netdev@vger•kernel.org
Subject: Re: [PATCH] myr10ge: again fix lro_gen_skb() alignment
Date: Wed, 29 Apr 2009 15:53:53 +0200 [thread overview]
Message-ID: <49F85BF1.1020501@cosmosbay.com> (raw)
In-Reply-To: <49F85945.7030900@myri.com>
Andrew Gallatin a écrit :
> Andrew Gallatin wrote:
>> For variety, I grabbed a different "slow" receiver. This is another
>> 2 CPU machine, but a dual-socket single-core opteron (Tyan S2895)
>>
>> processor : 0
>> vendor_id : AuthenticAMD
>> cpu family : 15
>> model : 37
>> model name : AMD Opteron(tm) Processor 252
> <...>
>> The sender was an identical machine running an ancient RHEL4 kernel
>> (2.6.9-42.ELsmp) and our downloadable (backported) driver.
>> (http://www.myri.com/ftp/pub/Myri10GE/myri10ge-linux.1.4.4.tgz)
>> I disabled LRO, on the sender.
>>
>> Binding the IRQ to CPU0, and the netserver to CPU1 I see 8.1Gb/s with
>> LRO and 8.0Gb/s with GRO.
>
> With the recent patch to fix idle CPU time accounting from LKML applied,
> it is again possible to trust netperf's service demand (based on %CPU).
> So here is raw netperf output for LRO and GRO, bound as above.
>
> TCP SENDFILE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
> hail1-m.sw.myri.com (10.0.130.167) port 0 AF_INET : cpu bind
> Recv Send Send Utilization Service
> Demand
> Socket Socket Message Elapsed Send Recv Send Recv
> Size Size Size Time Throughput local remote local remote
> bytes bytes bytes secs. 10^6bits/s % S % S us/KB
> us/KB
>
> LRO:
> 87380 65536 65536 60.00 8279.36 8.10 77.55 0.160 1.535
> GRO:
> 87380 65536 65536 60.00 8053.19 7.86 85.47 0.160 1.739
>
> The difference is bigger if you disable TCP timestamps (and thus shrink
> the packets headers down so they require fewer cachelines):
> LRO:
> 87380 65536 65536 60.02 7753.55 8.01 74.06 0.169 1.565
> GRO:
> 87380 65536 65536 60.02 7535.12 7.27 84.57 0.158 1.839
>
>
> As you can see, even though the raw bandwidth is very close, the
> service demand makes it clear that GRO is more expensive
> than LRO. I just wish I understood why.
>
What are "vmstat 1" ouputs on both tests ? Any difference on say... context switches ?
next prev parent reply other threads:[~2009-04-29 13:54 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-15 8:09 [PATCH] myr10ge: again fix lro_gen_skb() alignment Stanislaw Gruszka
2009-04-15 9:28 ` David Miller
2009-04-15 9:48 ` Brice Goglin
2009-04-15 10:02 ` David Miller
2009-04-15 13:01 ` Andrew Gallatin
2009-04-15 21:04 ` Andrew Gallatin
2009-04-15 23:42 ` David Miller
2009-04-16 8:50 ` Herbert Xu
2009-04-16 9:02 ` David Miller
2009-04-21 19:19 ` Andrew Gallatin
2009-04-22 10:48 ` Herbert Xu
2009-04-22 15:37 ` Andrew Gallatin
2009-04-24 5:45 ` Herbert Xu
2009-04-24 12:45 ` Andrew Gallatin
2009-04-24 12:51 ` Herbert Xu
2009-04-24 17:13 ` Rick Jones
2009-04-24 16:16 ` Andrew Gallatin
2009-04-24 16:30 ` Herbert Xu
2009-04-24 16:31 ` Herbert Xu
2009-04-27 8:05 ` Herbert Xu
2009-04-27 8:07 ` Herbert Xu
2009-04-27 9:32 ` David Miller
2009-04-27 11:01 ` Herbert Xu
2009-04-27 12:45 ` David Miller
2009-04-27 12:45 ` David Miller
2009-04-28 6:12 ` Herbert Xu
2009-04-28 15:00 ` Andrew Gallatin
2009-04-28 15:02 ` David Miller
2009-04-28 15:20 ` Herbert Xu
2009-04-28 15:44 ` Andrew Gallatin
2009-04-28 21:12 ` Andrew Gallatin
2009-04-29 13:42 ` Andrew Gallatin
2009-04-29 13:53 ` Eric Dumazet [this message]
2009-04-29 14:18 ` Andrew Gallatin
2009-04-29 15:26 ` Eric Dumazet
2009-04-29 17:28 ` Andrew Gallatin
2009-04-30 8:10 ` Herbert Xu
2009-04-30 8:14 ` Herbert Xu
2009-04-30 8:17 ` Eric Dumazet
2009-04-30 19:14 ` Andrew Gallatin
2009-04-23 8:00 ` Herbert Xu
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