2010/2/4 Matthew Dillon <dil...@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't have 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
