More awk

Eirik Nygaard has updated the One True awk in DragonFly to version 20040207. This temporarily broke the buildworld process, so if you tried a buildworld this afternoon and it failed with awk, it should now work. (Fixed by David Rhodus.)

Boot-time nfs issue fixed

Matt Dillon found that using short-form names in /etc/fstab would cause the DNS resolver to return “host not found”, even if there was just a timeout (which should result in “try again”) when first looking up that name. This is now fixed. If you found you could not mount NFS volumes at boot, but they worked when done manually after boot, this should fix it.

diffutils upgraded

Eirik Nygaard has committed diffutils 2.8.1 into the tree. This is similar to previous third-party software additions in that DragonFly-specific changes are managed through additional patches to original code, not by creating a DragonFly-only version of diffutils. Future upgrades are made much more easy using this method.

Negative NFS caching

Matt Dillon has added negative caching for NFS, meaning that NFS will now cache failed lookups, not just successful ones. He details the benefits like so:

“This makes a HUGE difference for programs which search nfs directories, such as compilers (the header file search path), make, and a few other utilities. NFS packet traffic can be reduced upwards of 90%. For example, with /usr/src mounted via NFS, building libc a second time without negative caching generates 66000 packets of NFS traffic in each direction, building libc a second time with negative caching enabled generates 9500 packets worth of NFS traffic, in EACH DIRECTION. While it is true that negative lookups are cached on the NFS server, the huge reduction in network traffic and equivalent reduction in synchronous read latencies result in radically reduced overheads across the board for operations which generate a lot of negative hits. A buildworld test with the default 3 second negative caching timeout went from 2265 seconds to 1900 seconds.”

Unixy system benchmarks

Ivan Voras has finished his benchmark of a system running FreeBSD, NetBSD, DragonFly and Linux. DragonFly does quite well, coming unsurprisingly close to the leader – FreeBSD 4.x. The difference would probably be more pronounced on a multiprocessor system, which wasn’t used in these benchmarks.

The right way to cvsup

For those of us from FreeBSDland, the kernel upgrade process is (well, recently) solidified to a number of steps including mergemaster. Matt Dillon noted that the DragonFly upgrading process is thus:

(update via cvsup)
cd /usr/src
make buildworld
make buildkernel KERNCONF=<kernel config file>
make installkernel KERNCONF=<kernel config file>
make installworld
make upgrade

The “make upgrade” step replaces mergemaster, and should be relatively faster. Credit for this goes to Sascha Wildner for asking for clarification on the dragonfly.bugs mailing list.

Getting a kernel crash dump

Matt Dillon posted this little note on how to get a kernel crash dump, which seems a good idea to archive – this may be useful again:

The best way is to get a kernel crash dump. If your swap area (typically ad0s1b) is large enough to accomodoate main memory, then ‘dumpon /dev/ad0s1b’ (and put ‘dumpdev=/dev/ad0s1b’ in your /etc/rc.conf), and then when it crashed and drops into DDB> type ‘panic’ and hit return twice and it should hopefully generate a crash dump.

For the crash dump to be really useful having the kernel.debug for the kernel that you are running is important. kernel.debug is built automatically when you buildkernel, but only the stripped ‘kernel’ version is actually installed. kernel.debug should still be sitting in the kernel build object directory which is usually /usr/obj/usr/src/sys/<KERNELNAME> (if you used ‘buildkernel’ to build your kernel).