Sorry, I did not know what to do with my report, so I am attaching it here since it seems to be the same problem.

I am running desktop Ubuntu 12.04 lts on 4 separate gigabit-networked machines, for my full-home media center, with the tuner installed in the 'server' (desktop install running NFS server) under mythtv, and 3 desktop install NFS clients in separate rooms. I had to upgrade the pre-existing 'server' (my learning platform) from 11.10 to 12.04 to match the clients because mythtv does not interoperate with differing versions, and I did not want to downgrade the clients to 11.10, I wanted a long term network install that is reliable and low-maintenance.

Now I have terrible network performance. The tuner works fine within the 'server', and I can view shows on the server, channel surf, record, play back, etc. no problems. Over the NFS network at the desktop clients, the media center system is almost completely broken.

If I start viewing a video media file, or listen to ripped audio, or i.e. open any media file at all, that is stored on the server, viewing on a client over the network, or if I attempt to edit the commercials out of shows on a client from over the network within mythtv editor, or even open a text file, the client will pause/hang for at least 30 seconds while 'loading' the file, and then finally it will start sequential streaming the media with OK performance on one or maybe two clients max - but when using Videolan VLC to view server media files on a client,  I had to increase the buffer by 10X (from 3 to 30 seconds of standard definition programming, approximately) to avoid long stuttering pauses in playback. Within mythtv frontend application at the client side, the video editing over the network is abominably slow, needing tenths of seconds, to seconds, to minutes, to hours, to completely hung, for the editor to respond to each keypress, getting slower all the time until it eventually grinds to a halt.

Listing directories, editing files, viewing media, using any of the text editors or media players I have installed, all have at least 30 seconds of delay on 'opening' (sending a command, either from a terminal window, or a nautilus window, or a text editor, or whatever), and the entire network slowly grinds to a standstill eventually, with mythtv locked in unusable state at the clients, even though it is still working fine on the server.

My server is a core 2 duo and so is my main media center client. The server is fully populated with 8gig of memory and terabytes of storage, and the client is sparsely populated with 2 gig of memory. I realize this is underpowered for hdtv media applications but surely a core 2 duo should be able to serve at least one standard definition media file at a time without any performance issues at all, and should be able to handle text editors with its eyes closed. I also have an i7 laptop client with 8 gig of memory and a terabyte of storage that suffers from the same poor network performance, even after disabling the troublesome Broadcom wireless power management, or even after plugging in the 1 gigabit wired connection and disabling of wireless.

I have no security at all configured on this network, and root squash is turned off so that I can edit or delete files without having to synchronize my clients accounts over NIS with Kerberos, which I do not even understand how to install let alone set up. I am just learning network admin, doing it on my own, slowly. This is by design a really primitive, drop-dead simple network install with only a hardware firewall protecting it. All transfers are synchronous, meaning there is no automounting going on. Everything is hard mounted, so when the desktop server hangs, so do all the desktop clients, if they happen to be actively running an NFS-supplied media file or etc. It took me months to learn how to do the hard mounting of encrypted volumes properly, needing to let it time out and retry until the encrypted raid password is entered. I did not encrypt the operating system just yet, not until I have everything working in the open, and it is starting to look like I will have to start over with another distribution entirely because of this bug!!

It seems there is an NFS tuning issue because there are some lost packets at the client side, and the NFS forums suggest increasing the number of threads. I am just now learning to debug and I have a dim perspective on these tuning issues at best. I am no Linux guru and have not increased the number of threads, because there is no way I could even use up the default number of threads with just a single user on this network, unless attempting to transcode from multiple machines at once and I do not have the disc space to support that just now anyway. I do not see any reason why NFS defaults should perform so badly that they lock up the system.

So far I have changed nothing on the NFS tuning, and started searching for answers in the bug reports, because it seems to me that for my pathetically underused hardware there should be no issues whatsoever running a simple, hard-mounted, single-user household media center with multiple networked clients and no security, even using conservative default tuning that ships with NFS, even if I occasionally run out of threads once in a blue moon there should be no performance issues whatsoever due to NFS. If anything, I would expect performance issues to be due to the hardware, but not of this character where things worsen over time so that after one day the network freezes.

Now here I find eerily familiar, long-standing bug reports that seem to incriminate kernel updates that changed the NFS auto tuning algorithm. I felt compelled to write an explanation of my own scenario since it is so different from the sophisticated, network-savvy implementations mentioned here. I thought perhaps something of importance could be learned, even from someone as ignorant as me, just because the implementation I am using is so dirt simple, eliminating many potential suspects.

I am wondering to myself, does Ubuntu intend to compete with Microsoft in the home media center market, or just let Microsoft eat their lunch? Or am I supposed to convert my Ubuntu network to run under Windows networking via Samba, and just flush NFS down the toilet? I really, really want to use NFS! I want the performance and I do not trust Windows networking. But it seems that even advanced Ubuntu users have been frustrated for over a year because of this bug! Should I change my entire network to Red Hat? I am completely unfamiliar with even their packaging application, I have no spare cash lying around, and my impression of CentOS is that it is highly stripped-down. I would have to build up all my proprietary hardware drivers from scratch and there is nothing even approaching the level of the Ubuntu support community for Red Hat.

Only solution I have found so far is to reboot all clients and server, after which NFS recovers temporarily, but still has long delays when starting up the streaming, and eventually grinds to a halt again, especially when mythtv fills its allocated disc space, after which it is a miracle if I can even task-switch out of its media player app in order to reboot all the clients and start over. It seems that even 'disc full' error messages are subject to the same limitations of this NFS bug, whatever it is.

One other thing I noticed is that mp4 transcoding jobs running in Handbrake on the clients, that seem to finish properly and close their output files, often actually do not finish writing to the server, leaving incomplete, corrupted files and requiring a second, third, or fourth attempt at transcoding. Also, the 32-bit machine I am using seems to have problems with the no-root-squash function -- while write-protecting transcoded output, it chowns its transcoded files attributed to user 'nobody', even though the other two (64-bit) clients have no problem chowning to root via NFS! Apparently, the older and slower the hardware, the worse the problems it experiences with NFS.

I apologize for the long, rambling comment on this bug report. I only even wrote it to indicate to the folks at Canonical that this NFS problem is affecting ordinary Ubuntu desktop users who are attempting merely to run the same full-house media center scenario that is being advertised on television for DirectTV and cable subscribers, and being implemented independently by Windows users familiar with mythtv and handbrake. Without a properly functioning NFS, Ubuntu is properly crippled.

I am not a programmer or system administrator, just a retired engineer with a little bit of hacking experience. A very little bit. After months learning to install and use Ubuntu properly, then I had to read documentation files and support group forums for a full year to get this far with the network setup, and now to find that the operating system I chose has a known, long-standing fatal networking flaw that I have been battling with all along feels like a big fat stick in the eye. Would some kind soul please remove that stick?

Does anyone consider it important or even kind to add warnings to the package manager, or even to the Ubuntu download page, so we do not all have to stumble across this networking show-stopper on our own? I chose Ubuntu for its ease of use and support, but here is a big fat gaping network hole that makes it impossible to even achieve Windows Media Center level of performance. Adding insult to injury, there is no advance warning anywhere about this networking problem.

Thanks for the learning experience, friends, but if this is the level of functionality I can expect from Ubuntu going forward, I am going to have no choice but to find another distribution that implements NFS correctly. I intend to keep increasing the complexity of my network, implementing full-network login accounts, printer sharing, etc. etc, and no way do I intend to do it all under Samba! Sorry, this is all the feedback I can provide on this bug, mainly that it affects me too and that it seems basic to NFS and that it is a show-stopper for my intended application. thx