On 12/12/11, Stephen Hemminger <[email protected]> wrote: > On Mon, 12 Dec 2011 06:43:45 +0800 > Barry Kauler <[email protected]> wrote: > >> On 12/7/11, Thomas Himmelmann <[email protected]> wrote: >> >> > Unionfs 2.5.10 don't work stable on kernel 3.0 and 3.1 for me. >> >> 2.5.10 is rock-solid with a 3.0.7 kernel for me. >> >> There is something that I found out about the Linux kernel, that might >> affect the stability of Unionfs... >> >> A little while ago, we found that one of these config option makes >> operation unreliable: >> >> CONFIG_SCHED_SMT >> SMT scheduler support improves the CPU scheduler's decision making >> when dealing with Intel Pentium 4 chips with HyperThreading at a cost >> of slightly increased overhead in some places. If unsure say N here. >> >> CONFIG_SCHED_MC >> Multi-core scheduler support improves the CPU scheduler's decision >> making when dealing with multi-core CPU chips at a cost of slightly >> increased overhead in some places. If unsure say N here. >> >> We were getting mysterious errors when using the 'cp' command. When >> copying a complete directory hierarchy, some files/directories were >> sometimes completely missing from the destination. There were no error >> messages. This has nothing to do with Unionfs (these errors were >> occurring in ext2/3 partitions outside of any layer filesystem), I am >> describing a fundamental flakyness of the kernel, not just the 3.x, >> earlier too. >> >> I discovered that turning off CONFIG_SCHED_SMT and CONFIG_SCHED_MC >> fixed it. It is probably only one of those that is the culprit though, >> probably CONFIG_SCHED_MC, but I never verified that. >> >> So, my kernel has: >> >> CONFIG_SMP=y >> # CONFIG_SCHED_SMT is not set >> # CONFIG_SCHED_MC is not set >> >> I recommend, configure your kernel the same, then see if you still get >> the problems with Unionfs 2.5.10. > > If those fixed your problems, then it means locking > is borked. I.e not a scheduler problem. What kind of device driver? > Could be bad disk controller driver. Did you report it to distro or kernel > mailing list? >
It is getting off-topic, but no, the problem was not with one computer. Different kernel; versions, different computers, even a brand new laptop. As it happened seemingly randomly, I could not reproduce it, and did not report it to lkml. Other Puppy Linux testers reported the same problem. Actually, ever since I first started using an SMP-enabled kernel with Puppy Linux, I left those two parameters disabled. It was only early this year that I enabled them, and we started hitting this random error problem. I disabled them again, and all is well. Anyway, this is o.t. I only brought it up, curious if it could be a factor in errors some people are reporting with latest Unionfs. If said person thinks that is highly unlikely, then they are welcome to ignore my suggestion. Regards, Barry Kauler _______________________________________________ unionfs mailing list: http://unionfs.filesystems.org/ [email protected] http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
