Hello Piergiorgio, On Mon, May 11, 2020 at 6:15 PM Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx> wrote: > Hi again! > > I made a quick test. > I disabled the lock / unlock in raid6check. > > With lock / unlock, I get around 1.2MB/sec > per device component, with ~13% CPU load. > Wihtout lock / unlock, I get around 15.5MB/sec > per device component, with ~30% CPU load. > > So, it seems the lock / unlock mechanism is > quite expensive. > > I'm not sure what's the best solution, since > we still need to avoid race conditions. > > Any suggestion is welcome! Would it be possible/effective to lock multiple stripes at once? Lock, say, 8 or 16 stripes, process them, unlock. I'm not familiar with the internals, but if locking is O(1) on the number of stripes (at least if they are consecutive), this would help reduce (potentially by a factor of 8 or 16) the costs of the locks/unlocks at the expense of longer locks and their influence on external I/O. -- Giuseppe "Oblomov" Bilotta
