Category Archives: Problem(s)

A phoronix benchmark creates a huge benchmarking discussion

The recent Phoronix benchmark which compared a release candidate of FreeBSD 9 with Oracle Linux Server 6.1 created a huge discussion in the FreeBSD mailinglists. The reason was that some people think the numbers presented there give a wrong picture of FreeBSD. Partly because not all benchmark numbers are presented in the most prominent page (as linked above), but only at a different place. This gives the impression that FreeBSD is inferior in this benchmark while it just puts the focus (for a reason, according to some people) on a different part of the benchmark (to be more specific, blogbench is doing disk reads and writes in parallel, FreeBSD gives higher priority to writes than to reads, FreeBSD 9 outperforms OLS 6.1 in the writes while OLS 6.1 shines with the reads, and only the reads are presented on the first page). Other complaints are that it is told that the default install was used (in this case UFS as the FS), when it was not (ZFS as the FS).

The author of the Phoronix article participated in parts of the discussion and asked for specific improvement suggestions. A FreeBSD committer seems to be already working to get some issues resolved. What I do not like personally, is that the article is not updated with a remark that some things presented do not reflect the reality and a retest is necessary.

As there was much talk in the thread but not much obvious activity from our side to resolve some issues, I started to improve the FreeBSD wiki page about benchmarking so that we are able to point to it in case someone wants to benchmark FreeBSD. Others already chimed in and improved some things too. It is far from perfect, some more eyes — and more importantly some more fingers which add content — are needed. Please go to the wiki page and try to help out (if you are afraid to write something in the wiki, please at least tell your suggestions on a FreeBSD mailinglist so that others can improve the wiki page).

What we need too, is a wiki page about FreeBSD tuning (a first step would be to take the man-page and convert it into a wiki page, then to improve it, and then to feed back the changes to the man-page while keeping the wiki page to be able to cross reference parts from the benchmarking page).

I already told about this in the thread about the Phoronix benchmark: everyone is welcome to improve the situation. Do not talk, write something. No matter if it is an improvement to the benchmarking page, tuning advise, or a tool which inspects the system and suggests some tuning. If you want to help in the wiki, create a FirstnameLastname account and ask a FreeBSD comitter for write access.

A while ago (IIRC we have to think in months or even years) there was some framework for automatic FreeBSD benchmarking. Unfortunately the author run out of time. The framework was able to install a FreeBSD system on a machine, run some specified benchmark (not much benchmarks where integrated), and then install another FreeBSD version to run the same benchmark, or to reinstall the same version to run another benchmark. IIRC there was also some DB behind which collected the results and maybe there was even some way to compare them. It would be nice if someone could get some time to talk with the author to get the framework and set it up somewhere, so that we have a controlled environment where we can do our own benchmarks in an automatic and repeatable fashion with several FreeBSD versions.


Are USB memory sticks really that bad?

Last week my ZFS cache device — an USB memory stick — showed xxxM write errors. I got this stick for free as a promo, so I do not expect it to be of high quality (or wear-leveling or similar life-saving things). The stick survived about 9 months, during which it provided a nice speed-up for the access to the corresponding ZFS storage pool. I replaced it by another stick which I got for free as a promo. This new stick survived… one long weekend. It has now 8xxM write errors and the USB subsystem is not able to speak to it anymore. 30 minutes ago I issued an “usbconfig reset

Stability problems solved (hardware problem)

After putting the disks of the 7-stable system which exhibited stability problems into a completely different system (it is a rented root-server, not our own hardware), the system now survived more than a day (and still no trace of problems) with the UFS setup. Previously it would crash after some minutes.

The ZFS setup with the changed hardware had a problem during the night before (like always after all my ZFS related changes on this machine), but on this machine I changed all locks in ZFS from shared locks to exclusive locks (this extended the uptime from 4