Mailinglist Archive: opensuse (3232 mails)

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network/disk/system performance
  • From: Dave Howorth <dhoworth@xxxxxxxxxxxxxxxxx>
  • Date: Wed, 2 Aug 2006 13:51:23 +0000 (UTC)
  • Message-id: <44D0ADB6.2090108@xxxxxxxxxxxxxxxxx>
I just got some surprising performance numbers.

I have three systems, call them A, B and C. A is a file server, B is supposed to be a fast server and C is my desktop. I'm trying to improve the performance of a job that normally runs on B and manipulates files on A, so I wrote a little test program. I ran it on all three machines. My test creates 10000 symlinks to a file. Symlinks and the file are accessed via NFS from A.

It was fastest on A (less than 1 second) - no surprise using local disk.
It took 5 seconds on C.
It took 23 seconds on B! Big surprise.

Anybody have any thoughts on what makes B so slow?

All are connected to each other through a gigabit switch. In addition, A and B have additional gigabit NICS connected directly to each other.

Here are some system details:

A: Tyan S5350 Tiger i7320 dual 2.8 GHz Xeon, 1 GB memory, lots of SATA
disks with 3ware controllers. SUSE 9.2
Intel PRO/1000 MT Dual Port NIC - quiescent during tests
Intel PRO/1000 MT Dual Port NIC - direct connect to B
Broadcom NetXtreme BCM5721 Gigabit NIC PCI Express - unused
Broadcom NetXtreme BCM5721 Gigabit NIC PCI Express - main network

B: Tyan S2882 Thunder K8S pro, dual Opteron 242, 8 GB memory,
fast SCSI local disks, SUSE 9.2
Intel EtherExpress PRO/100 S Server Adapter - unused.
Broadcom NetXtreme BCM5704 Gigabit NIC - direct connect to A.
Broadcom NetXtreme BCM5704 Gigabit NIC - main network.

C: Intel D925 / P4-3600, 2 GB memory, SATA local disk, SUSE 9.3,
Intel 82547EI Gigabit NIC - main network

While the test is running, 'vmstat 1' on B shows lines like:

procs -----------memory------------ -swap --io- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa

1 0 30716 2616544 42620 4389496 0 0 0 0 5698 4616 0 5 95 0

while on C it shows:

1 0 23820 737800 322640 372736 0 0 0 0 9311 12258 1 7 93 0

So C is managing nearly twice as many interrupts and three times as many context switches per second as B.

On quiet systems, nttcp shows very similar transmit (910 Mbps) rates from both B and C to A. The receive rate to C (930 Mbps) is a bit better than to B (840 Mbps). But I don't think there's anything wrong with the basic network.

Any ideas on how to improve B's performance would be very welcome.

Thanks, Dave

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