Date: Sun, 25 Mar 2007 21:00:35 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-chat@FreeBSD.ORG, deeptech71@gmail.com Subject: Re: 64bit timestamp Message-ID: <200703251900.l2PJ0Z8w058298@lurza.secnetix.de> In-Reply-To: <4605C415.7000206@gmail.com>
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deeptech71@gmail.com wrote: > Oliver Fromme wrote: > > FreeBSD's UFS2 already uses 96bit timestamps, where 64 bits > > are used for seconds and 32 bits are used for nanoseconds. > > Is that sufficient for you? > > What the hell for? What's your problem? In your first mail you seemed to be complaining that there isn't sufficient range and accuracy in the time stamps. I explained to you that there is indeed more accuracy than you thought, and now you complain that there's too much of it? To answer your question: Modern hardware is already fast enough that sub-microsecond accuracy is required. Also keep in mind that it is undesirable to change the on-disk- format of a file system every year. When the UFS2 format was designed, it should be sufficient at least for the needs of ten years in the future, possibly even more. So the provision for nanosecond accuracy is not far off. Ideally, two consecutive, non-parallel operations should give two different timestamps. That applies to creating or touching a file or other kind of resource, or even just calling the gettimeofday() function from within the same thread, or whatever. In reality that isn't the case today for FreeBSD for other reasons, but the timestamp accuracy of UFS2 would certainly be sufficient for that. 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 over-complicated nonsense. And Bjorn Shoestrap's book a danger to public health. I tried reading it once, I was in recovery for months." -- Cliff Sarginson
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