On Sat, Jul 21, 2012 at 09:25:50PM +0300, Uoti Urpala wrote: > Most of the time taken by cdebootstrap is wasted by dpkg on doing > useless file syncs: > > cdebootstrap --arch=amd64 unstable debian-tree/ > > from local package cache on ext4: 138 seconds > > on tmpfs where dpkg can't waste time on useless syncs: 21 seconds (and a > significant portion of that is used by package scripts with "sleep 1") > > So at least in this case the biggest performance problem by far is the > inappropriate use of fsync() or other disk synchronization primitives, > and CPU use for unpacking is pretty much irrelevant. My understanding is that dpkg uses fsync properly; that is, to guarantee the data is on the disk before exiting or doing things that require that data to be present. I don't currently see any bugs on dpkg that indicate that it is calling fsync needlessly or wastefully. If you see that behavior, could you please file a bug on dpkg? -- brian m. carlson / brian with sandals: Houston, Texas, US +1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187
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