On Thu, Feb 11, 2016 at 05:55:30PM +0100, David Sterba wrote: > The current practical default is ~4k on x86_64 (the logic is more complex, > simplified for brevity), the inlined files land in the metadata group and > thus consume space that could be needed for the real metadata. > > The inlining brings some usability surprises: > > 1) total space consumption measured on various filesystems and btrfs > with DUP metadata was quite visible because of the duplicated data > within metadata > > 2) inlined data may exhaust the metadata, which are more precious in case > the entire device space is allocated to chunks (ie. balance cannot > make the space more compact) > > 3) performance suffers a bit as the inlined blocks are duplicate and > stored far away on the device. > > Proposed fix: set the default to 2048 > > This fixes namely 1), the total filesysystem space consumption will be on > par with other filesystems. > > Partially fixes 2), more data are pushed to the data block groups. > > The characteristics of 3) are based on actual small file size > distribution. > > The change is independent of the metadata blockgroup type (though it's > most visible with DUP) or system page size as these parameters are not > trival to find out, compared to file size. This is a good compromise, and people that want higher numbers can always use the mount option. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
