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Description
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Since the zfs version property was introduced, "zfs list" has been slower. This is because when getting the properties, we now need to get the version property out of the objset itself. Since objsets' dnode files have 7 layers of indirection, we need to do at least 7 dependent reads, and cache at least 7*16K = 112K of data per dataset.
Even after deleting 24,000 snapshots on zion, this bug makes normal
tasks extremely painful. Just changing mountpoints (which require
iterating over children) on zion takes over 5 minutes. Running
'zfs list' on jurassic-x4600 takes half an hour. I don't know when
the S10u5 backport cut was made, but I would not release a supported
product with this bug present.
The ZFS test team is currently testing bits with changes that should fix this problem. Unless they find some showstopper, these changes should make it into SNV build 75. If possible, please install that build on zion ASAP and then please report the time needed to 1) run zfs list and 2) to change mountpoints.
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