From: "Vincent Sweeney" <v.sweeney@barrysworld.com>
To: <linux-kernel@vger.kernel.org>
Subject: PROBLEM: high system usage / poor SMP network performance
Date: Sun, 27 Jan 2002 22:23:17 -0000 [thread overview]
Message-ID: <004701c1a781$387d2570$0201010a@frodo> (raw)
I am the server admin for several very busy IRC servers with an ever
increasing user load but I've hit a severe bottle neck which after numerous
system tweaks and driver configuration changes I can only assume is related
to a performance problem with the Linux Kernel.
The server configurations are all identical:
Compaq Proliant 330R's with Dual Pentium III -800 MHz's & 384MB RAM
Intel NIC's using the Intel e100 driver
2.4.17 kernel
2 ircd processes per box
Here is a snapshot from 'top' :
9:51pm up 11 days, 10:13, 1 user, load average: 0.95, 1.24, 1.21
44 processes: 40 sleeping, 4 running, 0 zombie, 0 stopped
CPU0 states: 27.2% user, 62.4% system, 0.0% nice, 9.2% idle
CPU1 states: 28.4% user, 62.3% system, 0.0% nice, 8.1% idle
Mem: 385096K av, 376896K used, 8200K free, 0K shrd, 3588K
buff
Swap: 379416K av, 12744K used, 366672K free 58980K
cached
PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
7825 ircd 18 0 84504 82M 5604 R 89.5 21.9 6929m ircd
31010 ircd 20 0 86352 84M 5676 R 85.0 22.3 7218m ircd
When this snapshot was taken each ircd had 2000 users connect each. As you
can see I am using more than a single cpu's worth of processer power just on
system cpu and the ircd processes are using just over 50% of a single cpu!
Now in comparison, another server admin who runs a ircd on a single P3-500
Linux 2.4.x system with 3000 users reaches about 60% *total* cpu usage.
Likewise admins who run *BSD or Solaris can run with similar user
connections and barely break a sweat. I have tried setting all the network
performance tweaks mentioned on numerous sites and also using the cpu saver
option on the e100 driver but at best I have only seen a 1-2% cpu saving.
Naturally I would really like to know where / what is using up all this
system cpu so I would like to try profiling the kernel as I'm sure this is a
pure kernel network layer performance issue but I have no idea where to
start so does anyone have some advice / tips on where I should start?
Vince.
next reply other threads:[~2002-01-27 22:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-27 22:23 Vincent Sweeney [this message]
2002-01-27 22:42 ` PROBLEM: high system usage / poor SMP network performance Andrew Morton
2002-01-27 22:54 ` Alan Cox
2002-01-27 22:52 ` arjan
2002-01-27 23:08 ` Vincent Sweeney
2002-01-28 19:34 ` Vincent Sweeney
2002-01-28 19:40 ` Rik van Riel
2002-01-29 16:32 ` Vincent Sweeney
-- strict thread matches above, loose matches on Subject: below --
2002-01-29 18:00 Dan Kegel
2002-01-29 20:09 ` Vincent Sweeney
2002-01-31 5:24 ` Dan Kegel
[not found] ` <001d01c1aa8e$2e067e60$0201010a@frodo>
2002-02-03 8:03 ` Dan Kegel
2002-02-03 8:36 ` Andrew Morton
2002-02-12 18:48 ` Vincent Sweeney
2002-02-03 19:22 ` Kev
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