Messages in this thread | | | Date | Fri, 27 Aug 2010 00:22:46 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RFC PATCH 00/11] sched: CFS low-latency features |
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On Thu, 26 Aug 2010, Thomas Gleixner wrote: > On Thu, 26 Aug 2010, Peter Zijlstra wrote: > > > > Fudging fork seems dubious at best, it seems generated by the use of > > timer_create(.evp->sigev_notify = SIGEV_THREAD), which is a really > > broken thing to do, it has very ill defined semantics and is utterly > > unable to properly cope with error cases. Furthermore its trivial to > > actually correctly implement the desired behaviour, so I'm really > > skeptical on this front; friends don't let friends use SIGEV_THREAD. > > SIGEV_THREAD is the best proof that the whole posix timer interface > was comitte[e]d under the influence of not to be revealed > mind-altering substances. > > I completely object to add timer specific wakeup magic and support for > braindead fork orgies to the kernel proper. All that mess can be fixed > in user space by using sensible functionality. > > Providing support for misdesigned crap just for POSIX compliance > reasons and to make some of the blind abusers of that very same crap > happy would be a completely stupid decision. > > In fact that would make a brilliant precedence case for forcing the > kernel to solve user space madness at the expense of kernel > complexity. If we follow down that road we get requests for extra > functionality for AIO, networking and whatever in a split second with > no real good reason to reject them anymore.
I really risked eye cancer and digged into the glibc code.
/* There is not much we can do if the allocation fails. */ (void) pthread_create (&th, &tk->attr, timer_sigev_thread, td);
So if the helper thread which gets the signal fails to create the thread then everything is toast.
What about fixing the f*cked up glibc implementation in the first place instead of fiddling in the kernel to support this utter madness?
WTF can't the damned delivery thread not be created when timer_create is called and the signal be delivered to that very thread directly via SIGEV_THREAD_ID ?
Thanks,
tglx
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