From: Andrew Gallatin <gallatin@myri•com>
To: Herbert Xu <herbert@gondor•apana.org.au>
Cc: 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: Tue, 28 Apr 2009 17:12:20 -0400 [thread overview]
Message-ID: <49F77134.9030907@myri.com> (raw)
In-Reply-To: <20090428152047.GB7549@gondor.apana.org.au>
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
stepping : 1
cpu MHz : 2611.738
cache size : 1024 KB
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt
lm 3dnowext 3dnow rep_good pni lahf_lm
bogomips : 5223.47
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp
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.
Binding the IRQ to CPU0, and the netserver to CPU0, I see 6.9Gb/s
with LRO and 5.5 Gb/s with GRO. Monitoring the packet/byte counts
on the interface once per second, LRO looks like this:
Ipkts IBytes Opkts Obytes
588992 891733888 9758 644028
589610 892669540 9771 644886
589079 891865606 9754 643764
And GRO looks like this:
480309 727187826 7949 524634
480032 726768448 7947 524502
480000 726720000 7943 524238
Similarly, in this same scenario, binding the app/irq to the same
CPU and running mpstat -P 0 1 shows about 60%sys and 40% irq+softirq
while GRO shows about 45% sys and 55% irq+softirq.
I can't put my finger on it, but something about GRO is certainly
more expensive on these types of machines. I wish there was some
way you could see it, since it happens on every older AMD I try
it on. If you haven't been able to reproduce it, I'll see if I
can make it happen on a newer "slow" amd64 box I have tomorrow.
Drew
next prev parent reply other threads:[~2009-04-28 21:13 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 [this message]
2009-04-29 13:42 ` Andrew Gallatin
2009-04-29 13:53 ` Eric Dumazet
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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