Re: make -j4 gets stuck w/ ccache over NFS

[tridge@samba.org]

Mark,

 > I'm using ccache version 2.4 [1].  I just changed ~/.ccache to a symbolic
 > link to a directory which is NFS mounted [2].  The kernel source itself is
 > on a local FS.  With the ccache suitably primed, when I do a kernel compile
 > using 'make -j4' it seems to get stuck for seconds at a time.  When it gets
 > unstuck, it blows through a handful of files and then gets stuck again.

I'd suggest you first narrow down the problem to either being a
locking problem or a file IO problem. To do that, change lock_fd() in
util.c in ccache to just "return 0;". That will mean the ccache stats
file could become corrupted, but if it runs fast then you know that it
is a locking problem. I have noticed severe speed problem with NFS
locking on Linux previosly, which is why I mention this as a
possibility.

Note that removing this locking will not cause ccache to produce
incorrect object files, it will just mean the stats printed with
"ccache -s" may be inaccurate.

Cheers, Tridge

PS: I also wonder why you're not just using distcc. It's usually a lot
more appropriate in a distributed environment.