Obtaining real-world aged file systems

Obtaining real-world aged file systems

Posted Jul 7, 2006 2:53 UTC (Fri) by dlang (subscriber, #313)
In reply to: Obtaining real-world aged file systems by dlang
Parent article: The 2006 Linux Filesystems Workshop (Part III)

One thought that hit me just after posting the last comment,

now that there is the new timer base in the kernel, and we are nearing useability with the 'tickless' patches, how about setting up a special kernel with a custom timesource that's driven by the process writing the aged filesystem?

it knows the timestamp for all the origional filesystem actions, and it can find out all outstanding timers, after each filesystem action have it set a timer action for the time of the next filesystem action and then use the tickless capabilities to advance time up to that point (steping through each of the other timers on the way). this way the modified kernel and it's filesystem code would think that the replay took place in the same real-time that the origional actions that are being replayed took place in, andy delayed actions will take place appropriately (benifiting things if the delay would have helped in the origional, but happening between actions if they wouldn't have)

as long as the kernel isn't busy doing other stuff at the same time this replay should be very fast, and this avoids the haphazard benifits of trying to insert lots of sync calls.

David Lang

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