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Improving ext4: bigalloc, inline data, and metadata checksums

Improving ext4: bigalloc, inline data, and metadata checksums

Posted Dec 3, 2011 1:01 UTC (Sat) by walex (subscriber, #69836)
In reply to: Improving ext4: bigalloc, inline data, and metadata checksums by walex
Parent article: Improving ext4: bigalloc, inline data, and metadata checksums

BTW many years ago I persuaded the original developer of ext to not implement in it the demented BSD FFS idea of large block/small fragment, arguing that adaptive read-ahead and write-behind would give better dynamic performance, and adaptive allocate-ahead (reservations) better contiguity, without the downsides.

Not everything got implemented as I suggested, but at least all the absurd complications of large block/small fragment (for example the page mapping issues) were avoided in Linux, as well as the implied fixed ra/wb/aa.


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Improving ext4: bigalloc, inline data, and metadata checksums

Posted Dec 3, 2011 11:06 UTC (Sat) by nix (subscriber, #2304) [Link]

But of course we have had page-mapping-related bugs, in the *other* direction, from people building filesystems with sub-page-size blocks. (Support for this case is unavoidable unless you want filesystems not to be portable from machines with a large page size to machines with a small one, but it's still tricky stuff.)


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