From: "George Bonser" <george@gator.com>
To: "Rik van Riel" <riel@conectiva.com.br>
Cc: <linux-kernel@vger.kernel.org>
Subject: RE: 2.4 stable when?
Date: Fri, 20 Apr 2001 00:35:23 -0700
Message-ID: <CHEKKPICCNOGICGMDODJAEMICMAA.george@gator.com>
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Just to follow up on this ...

I am now running 2.4.4pre4 and it seems to be stable. If I reboot the
machine (or simply stop and restart apache) the load avg does go much higher
than I am used to seeing (near 50 for about 5 minutes or so) it does not
hang as previous kernels did.  I have the vmstat and top -i info if anyone
is curious.  It does not touch swap, though.


> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org
> [mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of George Bonser
> Sent: Sunday, April 15, 2001 8:39 AM
> To: Rik van Riel
> Cc: linux-kernel@vger.kernel.org
> Subject: RE: 2.4 stable when?
>
>
> >
> > > Is there any information that would be helpful to the kernel
> > > developers that I might be able to provide or is this a known issue
> > > that is currently being worked out?
> >
> > I never heard about this problem.  What would be helpful is to
> > send a few minutes' (a full 'load cycle'?) worth of output from
> > 'vmstat 5' and some information about the configuration of the
> > machine.
> >
> > It's possible I'll want more information later, but just the
> > vmstat output would be a good start.
> >
> > If the data isn't too big, I'd appreciate it if you could also
> > CC linux-mm@kvack.org.
> >
> > regards,
>
> Sounds good. I think I can do this.  Also, it appears that the problem is
> related to how busy the farm is.  The machines are load balanced
> in a "least
> connections" mode. There are 5 servers in the farm. Suppose I have 300
> connections to each machine and reboot one to load the new kernel.
>
> When that server comes back up it is handed 300 connections all
> at once. It
> seems (and this is subjective ... does it handle things differently with
> more than 256 processes?) that when I give the machine much more than 200
> connections, it is very slow to clear them.  It seems to have trouble at
> that point clearing connections as fast as it is getting them. If I have
> less than 200 connections initially, it seems to handle things OK.
>
> I tried to collect some data last night but it appeared to work ok. I will
> wait for the load to come up later today and try it during its peak time.
> While I could put the balancer into a "slow start" mode, 2.2 always seemed
> to handle the burst of new connections just fine so I didn't bother.
>
> The machine is a UP Pentium-III 800MHz with 512MB of RAM running Debian
> Woody. It is a SuperMicro 6010L 1U unit with the SuperMicro 370DLR
> motherboard. This uses the ServerWorks ServerSet III LE chipset
> and Adaptec
> AIC-7892 Ultra160 disk controller and on-board dual Intel NIC (only using
> eth0).
>
> I have cut the configuration pretty much to the bone, no
> NetFilter support,
> no QoS, no Audio/Video. Tried to get it as plain vanilla as possible (my
> first step when having problems).
>
> I was able to run 2.4.0-test12 in this application and did for quite some
> time. I don't recall trying 2.4.1 but I know I had severe problems with
> 2.4.2 and 2.4.3. Now that I think about it, I am not sure the farm was as
> busy back when I put 2.4.0 on it or that I ever rebooted during my peak
> period. This might have been a problem all along but I just never
> saw it. It
> seems to have to do with handing the machine a large number of connections
> at once and then a stream of them at a pretty good clip. It is
> getting about
> 40 connections/second right this minute but that should come up a
> bit in the
> next couple of hours.
>
> To be quite honest, I could run this on 2.2 forever, it is just a
> webserver.
> My only reason for using 2.4 would be to see if I can go SMP on
> these things
> when my load gets higher and I get some benefit of the finer
> granularity of
> 2.4 in SMP to serve a higher load with fewer machines than would
> be possible
> with 2.2. That, and just to beat on a 2.4 kernel and report any
> problems to
> you guys.
>
>
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