DragonFly BSD Digest

Paul Herman’s nanosleep() presentation is now on the DragonFly website.

Matt Dillon noted that:

makeoptions DEBUG=-g
options DDB
options INVARIANTS
options INVARIANT_SUPPORT


are the only options you need when building with debugging options on.

Skip Ford ported Tim Robbins’ FreeBSD port of Niels Provos’ NetBSD file descriptor allocation code. Normally I don’t post about code until it gets committed, but he posted some numbers on how well it improves things, as benchmarked by Niels Provos’ test program that opens/closes files repeatedly. The numbers seem to indicate a 50% speedup:

File Descriptors	Unpatched	Patched
1	0.765650	0.781279
2001	1.148484	0.789092
4001	1.546935	0.765657
6001	2.062582	0.781276
8001	2.515725	0.796906
10001	3.086061	0.796904
12001	3.632955	0.765654
14001	4.086098	0.757841
16001	4.515805	0.820343
18001	4.976759	0.812530
20001	5.429916	0.796905
22001	5.898652	0.773467
24001	6.336188	0.773455
26001	6.750268	0.804718
28001	7.179972	0.789091
30001	7.633110	0.781281
32001	8.070632	0.789091
34001	8.523771	0.796906
36001	8.953479	0.789092
38001	9.375370	0.765656
40001	10.117587	0.789090
42001	10.758238	0.789091
44001	11.367636	0.804718
46001	11.820781	0.812531
48001	12.453618	0.812530

Matt Dillon is bringing in resident executable support. This speeds loading of dynamically linked programs by saving a copy of their vmspace with vmspace_fork() in the kernel, and using that when executed instead of going through the regular, slower startup. This will replace prebinding.

Matt Dillon posted these preliminary numbers running a test program with Perl:

dynamic:	2.860u 2.668s 0:05.61 98.3%	87+231k 0+0io 0pf+0w
prebinding:	1.821u 2.095s 0:03.90 100.2%	34+202k 0+0io 1pf+0w
resident:	1.239u 1.846s 0:03.08 99.6%	137+280k 0+0io 0pf+0w
statically linked:	0.418u 0.867s 0:01.28 99.2%	808+616k 0+0io 0pf+0w

It is planned to make dynamic loading as fast as static. For those of you not familiar with the output of time, the first column is total time taken, the second is time taken to run the tested program, and the third is time consumed by system overhead. Yes, there are more columns than that. No, I don’t know what they mean.

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 García linked to a description of reiser4 which talks about journaling, along with some freaky illustrations.

Joerg Sonnenberger wrote up a proposal for background fsck, which he posted to the kernel discussion group. I”m pasting it wholesale.

(Matt Dillon has indicated he would prefer a journaling filesystem.)
Continue reading “Background fsck vs. journaling”

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”

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.

Jean-Marc Zucconi benchmarked FreeBSD 4.9-R, 5.1-R, 5.2-R and DragonFly on a multiprocessor system, and posted the large quantity of data this generated. It’s mashed into a table here:

(updated with better results for 5.2; ACPI was generating so many interrupts it was slowing his system.)

(see end of entry for his notes)
Continue reading “Benches being marked”

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“

Following up on recent discussion, ibotty listed ICU as another internationalization alternative.

Ryan Dooley brought up The CITRUS Project as a way to assist internationalization in DragonFly.

According to this benchmark, linked to by Xin LI, there’s file descriptor allocation code in FreeBSD 5 that may be worth the effort to port.

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”

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
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.