* Snapshots and VM resrouce
@ 2010-05-07 7:48 jason chan
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From: jason chan @ 2010-05-07 7:48 UTC (permalink / raw)
To: linux-btrfs
Try this:
create a 2GB file A in a subvolume vol_0
take a snapshot snap_1 of vol_0
Now see if their shared disk blocks give rise to shared VM resource:
dd if=vol_0/A of=/dev/null
dd if=snap_1/A of=/dev/null
And you will discover that the 2 dd sessions take same amount of time
to complete, vmstat will show that they incurred same amount of disk
IO. Now shouldn't vfs/vm be smart enough to know that they are
identical disk blocks and save the disk IOs?
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2010-05-07 7:48 Snapshots and VM resrouce jason chan
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