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dd vs sendfile with 1.8GB and "echo 3 > /proc/sys/vm/drop_caches"

dd bs=512 conv=fsync : 53 MB/s
dd bs=4k conv=fsync : 228 MB/s
dd bs=1M conv=fsync : 229 MB/s

sendfile: 226 MB/s

#linux #dd #sendfile #shell

The operating system’s memory page size is by default 4096 bytes. Using a block size smaller than this and you’re won’t be using the unit page used for byte coping to it’s full potential, and therefore wasting clock cycles between IO system calls.

Turned on squashfs compression for FedoraBook. I was afraid, that with compression enabled, xdelta would not produce small deltas. But it does!! 😀
root.img changed from 4.1GB to 1.8GB
Delta for no-change: 20MB
Delta from current Fedora 29 to Fedora 30: 633MB

#xdelta #squashfs #fedorabook #fedora #linux