On Sun, 2016-04-17 at 22:24 +0200, Samuel Thibault wrote: > Hello, > > Thanks for the investigation. I have added the attached patch to the > gnumach running on the buildds. That'll revert to the old page cache > policy, which seems to be reverting to the previous performance.
Build times are now back: qemu-system ... -device cache=writeback gcc: 5.3.1-14 glibc: 2.22-5 hurd: 0.7.git20160320-2 gnumach: 1.6+git20160311-1 with 99-revert-page-cache-policy.patch real 43m47.740s It seems to be more unstable though, than the slower non-reverted version. > Looking at ps -feMj, it seems that it's ext2fs which consumes much more > CPU time, thus increasing overall wallclock time. It'd probably be > interesting to profile ext2fs, to see what takes longer. Perhaps it's > the hash table which is less efficient since with the new page cache > policy there are much more cached files? Are you preparing ext2fs for profiling? .../pkg-glibc/glibc: hurd-i386: Fix recording profiling from ext2fs
