kernel work week of 3-Feb-2010 HEADS UP

[Michael Neumann]

2010/2/4 Matthew Dillon <dillon at apollo.backplane.com>

:Awesome :)
:
:Would such a SSD cache also improve write performance of a HAMMER file
:system?
:To improve write performance we'd probably need to put the UNDO/REDO log
:on a SSD...

    No, the first iteration is strictly a clean slaved throw-away copy.

    Writes run to the actual media and free any related underlying swap
    copy.  A new swap copy may be made later when the cached VM page
    associated with the write cycles back out of main memory.Understood. So this basically means that when I do a read-after-write I don'thave to read from disk as it's either in memory, or if I wait too long, it's moved
to swap-cache and I still can access it quickly.
:And will the new system also cache mmap'ed data of a file?
:
:Regards,
:
:  Michael

    Yes.  Both read() and mmap()'d data are backed by VM pages and are
    applicable to the cache.Great! Regards,  Michael