--- Kevan Benson <kbenson at a-1networks.com> wrote: > On Monday 27 November 2006 10:54, Martin Knoblauch wrote: > > first of all, please CC me on any reply, as I am only subscribed > to > > the digest. > > > > OK. Here is the problem. Said kernel (from 4.4) seems to have > problems > > with file-locking when the system is under high, likely network > > related, > > load. The symptoms are things using file locking (rpm, the > user-space > > automounter amd) fail to obtain locks, usually stating timeout > > problems. > > > > The sytem in question is a HP/DL380G4 with dual-single-core EM64T > CPUs > > and 8GB of Memory. The network interfaces are "tg3". It happens > with > > both CentOs and RHEL4. > > > > The high load can be triggered by copying three 3 GB files in > parallel > > from an NFS server (Solaris10, NFS, TCP, 1GBit) to another NFS > server > > (RHEL4, NFS, TCP, 100 MBit). The measured network performance is > OK. > > During this operation the systems goes to Loads around/above 10. > > Overall responsiveness feels good, but software doing file-locking > or > > stuff like opening a new ssh connection take extremely long. > > > > So, if anyone has an idea or hint, it will be highly appreciated. > Hi Kevan, > NFS has known problems with flock. man flock(2) specifically notes > this. Which file locking mechanism (flock or fcntl) does your > system use predominantly (that is, how do the applications that > uses NFS lock their files)? > Now, amd uses fcntl to do the locking of /etc/mtab. But I do not believe that the locking problem is restricted to NFS. To me it looks like all kind of files are affected. > NFS v4 has some major strides towards better locking, but it's been > long enough since I dealt with this that I'm not sure if it actually > solves anything (although it looks like it does). > You might want to try NFS v4 if possible. > Due to the environment (a very high number of potential NFS servers, all running NFSv3) V4 is not an option. And, as I said, the locking problems occur on local files. NFS is only related to the high-load condition that seems to accompany the locking problems. Cheers Martin ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de