Date: Thu, 4 Nov 2010 19:23:29 +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: <201011041823.oA4INTIL097844@lurza.secnetix.de> In-Reply-To: <20101104143542.GA628@icarus.home.lan>
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Jeremy Chadwick wrote: > On Thu, Nov 04, 2010 at 03:29:22PM +0100, Oliver Fromme wrote: > > What kind of tuning do you apply to those file systems? > > > > I'm asking because I can't really reproduce those results. > > On a machine with plenty of RAM I've created memory disks > > for obj and src, which should at least be as fast (probably > > even faster) than an SSD. Buildworld was somewhat faster, > > compared to standard (well-tuned) UFS+SU filesystems on a > > fast SATA HDD, but not _that_ much faster. In fact the > > difference was small enough that I stopped using memory > > disks and returned to using UFS+SU+noatime (and a few other > > tuning options) on a HDD. > > > > So, if you experience a _dramatic_ speed-up when using SSDs > > for buildworld, I would really very much like to know why > > this is the case, and what kind of tuning you performed. > > Literally: absolutely no tuning. I treat the SSD the exact same as I > would a standard mechanical HDD: install FreeBSD on it, and that's that. > > I imagine the performance difference greatly depends on what SSD you're > actually using. Again, the Intel drives have the highest IOPS out there > (at least in the consumer-grade market), and I can't justify the cost of > an SLC-based drive, so I stick to MLC. > > Possibly you and I have different interpretation of what "dramatic" > means? :-) My opinion is that cutting 6-7 full minutes off a > buildworld is pretty dramatic. Well, here are some hard numbers: 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 10:13 vs. 10:04 is not "dramatic". I don't think there's a way I can cut 6-7 minutes from that with current (and affordable) hardware. 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 "C is quirky, flawed, and an enormous success." -- Dennis M. Ritchie.
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