Date: Fri, 5 Nov 2010 08:56:52 +0100 (CET) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-fs@FreeBSD.ORG, freebsd@jdc.parodius.com Subject: Re: Using an SSD "disk" for / Message-ID: <201011050756.oA57uqdW030090@lurza.secnetix.de> In-Reply-To: <201011041823.oA4INTIL097844@lurza.secnetix.de>
next in thread | previous in thread | raw e-mail | index | archive | help
Oliver Fromme wrote: > With /usr/src and /usr/obj both on the same SATA-300 HDD, > a buildworld takes 10 minutes and 13 seconds. > > With /usr/src and /usr/obj on separate memory disks, > a buildworld takes 10 minutes and 4 seconds. > > This is stable/8 with empty /etc/src.conf, i.e. a complete > buildworld. The machine is an AMD Phenom II X6 (hexacore). I think I should give some more information about the system that I used for the test. The HDD is accessed via ahci(4) and ada(4) with NCQ. This might make a small difference, though I haven't benchmarked it. src and obj are mounted with noatime. In the memory disk case, src was even mounted read-only, and obj was mounted async. I made sure that there was no swapping / page-out activity during the memory disk test, so all the data really stayed in RAM (which should be even faster than an SSD, I assume). The system was otherwise idle, gstat(8) basically showed nothing on ada0 during the memory disk test. The following sysctl tunings are in effect: vfs.hirunningspace=8388608 vfs.lorunningspace=1048576 vfs.read_max=32 vfs.ufs.dirhash_maxmem=33554432 kern.sched.preempt_thresh=220 (I've got more things in /etc/sysctl.conf, but the rest shouldn't affect file system performance or buildworld, I think.) The kernel is running with HZ=300 (unfortunately HZ isn't dynamic in FreeBSD, so I'm using 300 as a trade-off). AUDIT and MAC are disabled. 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 "When your hammer is C++, everything begins to look like a thumb." -- Steve Haflich, in comp.lang.c++
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201011050756.oA57uqdW030090>