On Sun, Mar 11, 2007 at 01:28:22PM +1100, Con Kolivas wrote: > >make -j 5 ccache > > beryl ok good awful > > galeon good good bad > > mp3 good good bad > > terminal good good bad/ok > > mouse good good bad/ok ... > >RSDL makes most of the noyield hit back in normal make and then some > >with ccache. Impressive. But ccache is still destroying interactivity > >somehow. The ccache effect is fairly visible even with non-parallel > >'make'. > > Ok I don't think there's any actual accounting problem here per se > (although I did just recently post a bugfix for rsdl however I think > that's unrelated). What I think is going on in the ccache testcase is > that all the work is being offloaded to kernel threads reading/writing > to/from the filesystem and the make is not getting any actual cpu > time.
I don't see significant system time while this is happening. > This is "worked around" in mainline thanks to the testing for > sleeping on uninterruptible sleep in the interactivity estimator. What > I suspect is happening is kernel threads that are running nice -5 are > doing all the work on make's behalf in the setting of ccache since it > is mostly i/o bound. The reason for -nice values on kernel threads is > questionable anyway. Can you try renicing your kernel threads all to > nice 0 and see what effect that has? Obviously this doesn't need a > recompile, but is simple enough to implement in kthread code as a new > default. Sorry, little to no benefit. -- Mathematics is the supreme nostalgia of our time. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/