PFC wrote:
> >> This may have been mentioned before, but perhaps there could be a >> "trickle-out" option along the lines of "if the hard drive is idle (and >> optionally only if it's spun up), slowly write out the changes to the >> disk structure." This could also be paired with keeping as much of the >> data in memory as necessary to mantain the speed boost that r4 gets from >> temporal locality of reference, possibly just giving it to the system >> cache. > > > Hm actually, this looks a lot like read-ahead algorithms, but > instead it's "write-ahead" : > > For instance : > - Sequential writes on large files should stream through the cache. > - Random writes or small file writes should be kept as long as > possible in dirty pages so they can be coalesced into larger writes > with a better disk layout on flush, or not written at all if it was > temp files from a make, for instance. > > Do the file copying programs open their output files with > O_SEQUENTIAL ? If so, there is information to exploit... > > You can change them to do so....
