* Borislav Petkov <b...@alien8.de> wrote: > On Fri, Nov 22, 2013 at 04:39:11PM +0100, Ingo Molnar wrote: > > > I see no problem with that - it's basically like util/*.c is, just > > between tools. > > But why? Why it is a good thing to have to pay attention to linking > to 10 minilibs when you're using 10 utilities for your tool instead > of a small number of topic libraries, 2-3 tops?
It's a single line added to the Makefile, the moment a .h is used for the first time. That's not any appreciable overhead. This would also allow us to farm out most of tools/perf/util/ into tools/lib/, without any noticeable changes in build performance or build dependencies. Down the line it would (hopefully) result in code improvements to these infrastructure bits, sourced from different tools. > What's wrong with the split: > > * generic stuff > * trace events > * perf events > > ? Well, the natural evolution of interfaces ended up with such a split up: comet:~/tip/tools/perf> ls util/*.h util/annotate.h util/hist.h util/strbuf.h util/build-id.h util/intlist.h util/strfilter.h util/cache.h util/levenshtein.h util/strlist.h util/callchain.h util/machine.h util/svghelper.h util/cgroup.h util/map.h util/symbol.h util/color.h util/parse-events.h util/target.h util/comm.h util/parse-options.h util/thread.h util/cpumap.h util/perf_regs.h util/thread_map.h util/data.h util/pmu.h util/tool.h util/debug.h util/probe-event.h util/top.h util/dso.h util/probe-finder.h util/trace-event.h util/dwarf-aux.h util/pstack.h util/types.h util/event.h util/quote.h util/unwind.h util/evlist.h util/rblist.h util/util.h util/evsel.h util/run-command.h util/values.h util/exec_cmd.h util/session.h util/vdso.h util/fs.h util/sigchain.h util/xyarray.h util/header.h util/sort.h util/help.h util/stat.h If we want additional structure to it then it should be done via the namespace, not by forcing them into bigger .a's. So this kind of extra structure makes sense: api/types/rbtree.h api/types/strbuf.h api/formats/dwarf/unwind.h api/kernel/pmu.h api/kernel/cgroup.h api/kernel/debugfs.h But stuffing them into types.a, formats.a, kernel.a, not so much. > With "generic stuff" being something like glibc. There's hardly a > tool that needs/links to *all* of glibs's functionality yet glibs > doesn't get split. Do you see what I mean? glibc being such a catch-all library is: - partly a historic artifact caused by other constraints that don't affect our tooling landscape here - partly a political artifact caused by thinking that does not affect our tooling landscape - partly a technological mistake. There's no need for us to repeat that, at least at this stage. > > What dependencies do you mean? The only constraint is to not make > > it circular - but that's easy to do if they are nicely separated > > per concept. I don't think rbtree.h ever wants to include cmdline > > processing or debugfs processing. > > But if you have a single .a library, you don't care about which > minilibrary to link to what. You basically do take libkapi.a and > you're good to go - no need to hunt every dependency. You still need to figure out the .h file - at that point, when you are using it for the first time in your tool project, you add the .c file to the Makefile - it's not hard and there are real advantages. > With the split above, for example, libkapi.a links to glibc only. > libtraceevent.a and libperfevent.a both link to libkapi.a and glibc. > It is all nice and clean. It does not look that nice and clean once I consider all the nice helpers that exist in util/*.[ch] - and which we'd like to share as well. Thanks, Ingo -- 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/