On Mon, Apr 08, 2013 at 05:32:50PM +0200, Ingo Molnar wrote: > > * Frederic Weisbecker <fweis...@gmail.com> wrote: > > > 2013/4/4 Stanislaw Gruszka <sgrus...@redhat.com>: > > > On Thu, Apr 04, 2013 at 02:31:42PM +0200, Frederic Weisbecker wrote: > > >> I don't know. I'm not convinced userland is the right place to perform > > >> this kind of check. The kernel perhaps doesn't give guarantee about > > >> utime/stime precision but now users may have got used to that scaled > > >> behaviour. It's also a matter of security, a malicous app can hide > > >> from the tick to make its activity less visible from tools like top. > > >> > > >> It's sortof an ABI breakage to remove such an implicit protection. And > > >> fixing that from userspace with a lib or so won't change that fact. > > > > > > I think number of fields in /proc/PID/stat is not part of ABI. For > > > example commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 add various > > > new fields at the end of the file. What is imported to keep unchanged > > > ABI is not changing order or meaning of fields we already have. > > > > Oh I wasn't considering the layout of the proc file but the semantic > > change in its utime/stime fields. > > Btw., even the ordering of fields in /proc/PID/stat might be an ABI, iif an > application relies on it and breaks if we change it.
Sure, but it seems there are exceptions as in the above mentioned commit. > > What matters is what applications do, not what we think they do or what we > think > they should do in an ideal world. Agreed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/