Hi, On Mon, 02 Jan 2012, Petter Reinholdtsen wrote: > [ Mike Hommey ] > > While this is stricly true, there are still two fsync()s occuring on each > > package unpack, making the whole thing still slow when installing many > > packages at a time. > > > > These happen for /var/lib/dpkg/updates and /var/lib/dpkg/tmp.ci. > > [ Raphael Hertzog ] > > This is on purpose. > > Can you explain in which situation where --force-unsafe-io is used > that you believe these fsync()s to be an advantage? I've tried to > come up with such scenarios without any luck so far.
This is an option that we wish it did not exist. > The users of --force-unsafe-io seem to be those that know that if > something go wrong during installation, they scratch everything and > start again, and finishing quickly is more important than handling > power outages. One example is building live CDs. Another is > installing the system for the first time. A third is creating chroots > for testing. In all these cases any power outage or other system > failure will make one erase everything and start over, and there is no > need for dpkg to keep an consistent state. > > I would love my distro upgrade test to become faster and thus hope > also these fsyncs can go away. I install stable in a chroot, > dist-upgrade to testing, and check the rsult. If the something go > wrong I remove the chroot and start over, so there is no need for any > sync to disk. :) The proper approach is to enhance your testing tools to use "eatmydata" to really disable all fsync() and not only those of dpkg. --force-unsafe-io has not been meant for those use case at all, it was meant for some users to gain back some performance lost on supplementary fsync() that have been added to dpkg. It was not meant to disable all fsync() and in particular not those on the database. Cheers, -- Raphaël Hertzog ◈ Debian Developer Pre-order a copy of the Debian Administrator's Handbook and help liberate it: http://debian-handbook.info/liberation/ -- To UNSUBSCRIBE, email to debian-dpkg-bugs-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
