Date: Tue, 8 May 2007 00:28:12 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-stable@FreeBSD.ORG, marsgmiro@gmail.com Subject: Re: mfs and buildworlds on the SunFire x4600 Message-ID: <200705072228.l47MSCSr048972@lurza.secnetix.de> In-Reply-To: <28edec3c0705071447t64eb6ea1n7a18550d4af6d883@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Mars G. Miro wrote: > Oliver Fromme wrote: > > By the way, what are you actually trying to do? What is > > your goal? Do you need to reduce the buildworld time? > > as i've mentioned in my original email, does mfs speed up I/O stuff ? Sometimes it does. But most of the time, a real disk partition with soft-updates on it is just as fast. With soft-updates, writing is asynchronous, i.e. it goes to RAM first, just like a memory disk. The data is later committed to disk in the background, so the processes don't have to wait for it. And once the data is in the cache, reading is just as fast (or even faster) as a memory disk. Note that /usr/src will fit in the cache easily if you have several GB of RAM. I usually have a memory disk as /tmp, but that's really just for historical reasons. And it's easier to clean up -- just umount it. ;-) > there's been a lot of threads in teh past that a buildworld on mfs > increases speed --- tho it might not be the appropriate test for > high-end machines (speaking of w/c I just gots a T2000). It depends on what exactly you want to test, and for what reason. You probably have already wasted much more time with your experiments and testing than you can ever save by using mfs for buildworld. > there's prolly other appropriate apps/tools for mfs-testing ... I don't think it makes much sense to benchmark mfs. It is a known fact that a real tmpfs (like Solaris and Linux have) would be better. I think it's even listed on the FreeBSD ideas web page, but nobody is actively working on it, AFAIK. On the other hand, I'm not 100% convinced that it would be worth the effort either. It would be interesting to see how ZFS on a swap-backed vnode device would perform on FreeBSD 7-current (with and without compression). Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200705072228.l47MSCSr048972>