Messages in this thread | | | Subject | Re: [GIT PULL] Performance Counters for Linux | From | Marcel Holtmann <> | Date | Thu, 11 Jun 2009 22:49:17 +0200 |
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Hi Ingo,
> > What the "keep it in the kernel sources" approach hopefully allows is > > > > - taking advantage of new features in a timely manner. > > > > NOT with some ABI breakage, but simply things like supporting a > > new CPU architecture or new counters. The thing that oprofile > > failed at so badly in my experience. > > > > - Make it easier for developers, and _avoiding_ the horrible > > situation where you have two different groups that don't talk > > well to each other because one is a group of user-space > > weenies, and the other is a group of manly kernel people, and > > there is no common ground. > > Yes, very much agreed. > > Btw., here are a couple of other arguments why i find it useful to > have the tools/perf/ in the kernel repo: > > 1) Super-fast and synchronized release cycles > > The kernel is one of the fastest moving packages in Linux - most > user-space packages have (much!) longer release cycles than 3 > months.
that might be true for some projects, but for others this is wrong. You are just making an assumption out of thin air.
> A tight release schedule forces a certain amount of release > discipline on tooling as well - so i'm glad that the two will be > coupled. It's so easy for a promising tool to degrade into > tinkerware with odd release cycles with time - if it's part of the > kernel then at least the release cycles wont be odd but at precise 3 > months.
And you can't do that within a perf.git tree on kernel.org because?
> 2) Performance _matters_ > > This is an argument pretty specific to perfcounters: Performance > analysis tools under Linux suck pretty summarily. Yet, one of the > major strengths of Linux is (or at least used to be) performance. So > i find it very fitting that the kernel community takes performance > analysis tooling into their own hand. > > 3) Strict quality control under a proven mode > > In the kernel repo i can be sure that: > > - No one will even think of adding autofools to tools/perf/.
That argument is non-sense. While autoconf/automake is maybe not to your liking, nobody forces you to use it. Projects like git, iw etc. do perfectly fine without it. I don't mind having autoconf/automake around.
> - No one will send us code with Hungarian notation and two spaces > tabulation.
What kind of shitty argument it is that. I enforce kernel coding style in my userspace project all the time. No problem with that.
> - No one will put getopt.h into the code
And that is so bad because?
> - No one will rewrite it in some weird language
And they can do as they please. You don't have to accept the re-write. These are all non-sense arguments. If you maintain a userspace project properly then you will not see any of these problems.
> I can point contributors to well-established kernel coding > principles, without having to argue no end about them.
Come on. A lot of projects use kernel coding style nowadays. That is not a problem here.
> All in one - the Linux kernel is a fire breathing monster engine > when it comes to producing good software. Who says it that that this > infrastructure and experience can only be used to produce kernel > space code?
And who says that all userspace people have no idea what they are doing. We have a lot of successful project that follow almost the same rules as the kernel.
> 4) Code reuse > > We actually use code from the kernel: list.h primitives and > rbtrees.c. We privatized them for now under > tools/perf/util/rbtree.[ch] and tools/perf/util/list.h because > there's some header and type pollution in them, but it would be nice > to include them directly and share the facilities.
Lets see if you are making up an argument or if you are really trying to work this out and solve it.
> 5) Reality check for kernel developers > > I think kernel hackers need a reality check too. It's easy to say > that user-space sucks - but now there's a way and channel that > frustration via direct action and make a real difference. I do hope > that the extra superfluous mental energies visible in this thread > can be used for good purposes too ;-) > > 6) It's a lot of fun > > I never thought i'd say that - but hacking properly structured > user-space code in the kernel repo is serious fun. It's even > relaxing at times: i can be reasonably sure that i wont crash the > kernel. > > All in one, we did this because we found that it produces better > code in practice and does it faster - and i dont think we should > rigidly limit the kernel repo to kernel-space projects alone.
Linus has a bad expierience with oprofile and wants to try something new and I can follow that argument to a certain degree. I don't agree with it, but that is fine.
So you are saying that only good code comes from including it into linux-2.6.git and otherwise you will never get there. Have you actually tried to maintain this in a separate repository on kernel.org?
Regards
Marcel
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