A journaling journey

Discussion continues on journaling, soft updates, and background fsck. Jeroen van Gelderen linked to “Design Evolution of the EROS Single-Level Store” while talking about journaling meta-data, and Matt Dillon mentioned that he and David Rhodus are putting together a kernel API for journaling, so that some ambitious person can build it. Matt Dillon also pointed out he favors journaling because softupdates is a complex beast, and modern IDE drives are somewhat undependable when it comes to the way they lay down data. As an added bonus, Diego Calleja GarcĂ­a linked to a description of reiser4 which talks about journaling, along with some freaky illustrations.


Matt Dillon noticed in a thread on the freebsd-hackers mailing list (see here for original post, and look for articles following that have [CHECKER] in the subject) that the M_NOWAIT command is being used incorrectly in a number of places, both in DragonFly and in FreeBSD.

I’m just pasting the rest of his post, as it’s not something that boils down easily:
Continue reading “M_NOWAIT NOGOOD”

Plans and other plans

As part of a discussion about internationalization, Matt Dillon mentioned he plans to finish IPC this weekend as it would be a useful implementation method. He also mentioned offhand that the first release of DragonFly could be in June/July.

645dx tricks

Bernhard Valenti found he had to put “set hw.ata.ata_dma=0” in the boot loader to get his 645DX-based motherboard ATA working. Jeroen Ketema also found that write caching had to be off: “set hw.ata.wc=0

Make upgrade

Because of the GCC2/GCC3 work (which, incidentally, will allow other compilers like TenDRA to be used in system compilation), do a “make upgrade” after your next installworld. This will clean up now-stale compiler files, plus update files in rc.d and so on.

Benchmark setups

In a discussion about benchmarks, it was noted that /etc/malloc.conf changes can help benchmarks tremendously. Rahul Siddharthan suggested ‘/etc/malloc.conf -> H' and Jeremy Messenger suggested '/etc/malloc.conf -> aj

Also, Matt Dillon made a number of suggestions on what to check when benchmarking DragonFly vs. FreeBSD (4 or 5)

Matt Dillon quote follows:
Continue reading “Benchmark setups”

Prelinking reported

Simon ‘corecode’ Schubert pointed out prelinking should be mentioned on the 2003 report; here’s the text that will soon show up on that report:

Prelinking capability was added to DragonFly by Simon ‘corecode’ Schubert, which allows faster loading of applications that use a large number of dynamic libraries while running, like Qt/KDE. It is not currently hooked into the system or any port building process.

ssh bug fixed

Matt Dillon fixed an apparently long-term problem in OpenSSH where a server can hang because it has a lot of data to send, but no immediate resources to do it with.

Reproduce it like so:
limit filesize 64k
ssh remotebox -n cat /usr/share/dict/words | cat > junkfile

Jump on journaling

David Rhodus has the journaling filesystem code from Apple located in vfs_journal.c and vfs_journal.h. He estimate it’d take 2-3 (long) days of work to get it worked into the system, which would mean no more long fscks after unlcean shutdowns. Any takers? Everyone would love you for it.

Idle hands do the daemon’s work

Eirik Nygaard was looking for something to do; Max Laier pointed out removal of #if defined(__FreeBSD__) / #if __FreeBSD_version > 5 would help, and Jeffrey Hsu indicated backporting the UFS2 size extensions would also be good.

I’ll quote my own followup to say there’s plenty of non-coding tasks available, too.

Paying off already

David Rhodus imported Hyperthreading changes from FreeBSD which allow you to automatically use Hyperthreading on supported CPUs with just the regular multiprocessor options turned on in your kernel; e.g. options SMP, options APIC_IO.

However, the DragonFly version has no idling loops in it to reduce CPU resource contention. Because of the way DragonFly schedules per-CPU/sends IPI messages, there’s no performance issue caused by multiple CPUS HLTing. Already, a benefit.