Hello, On ketvirtadienis 21 Spalis 2010 00:11:05 Chanoch (Ken) Bloom wrote: > This issue was current at the beginning of 2010, around the time Bug > #567089 was filed and discussed. It's been fixed in the kernel since > then. See http://lwn.net/Articles/322823/, and > http://lwn.net/Articles/326471/ > > Does it still affect the shipping Debian kernel?
ext3 is not a very big problem from my experience unless there is heavy I/O in the background. I use 2.6.35 kernel. > The problem here was "data=ordered". ext3 also suffered from this > problem, since its default was "data=ordered". > In brief, ONE fsync() call cost about as much as ONE sync() call. > The solution was "don't use data=ordered" (and Linus patched the > kernel to change the default) then fsync() will be suitably faster. ext4 and especially btrfs take a huge (in 10x-60x range) performance hit due to those repetitive fsync() or sync() calls. But since dpkg keeps calling sync(), performance suffers even if dpkg is not writing to ext4/btrfs file system directly. My benchmarks are here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=588254 -- Modestas Vainius <modes...@vainius.eu>
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