Date: Wed, 23 Feb 2011 14:30:13 +0000 From: Alexander Best <arundel@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r218967 - head/sys/kern Message-ID: <20110223143013.GA67074@freebsd.org> In-Reply-To: <20110223142108.GP78089@deviant.kiev.zoral.com.ua> References: <201102231256.p1NCuPHN056220@svn.freebsd.org> <20110223131228.GN78089@deviant.kiev.zoral.com.ua> <20110223135734.GA62693@freebsd.org> <20110223142108.GP78089@deviant.kiev.zoral.com.ua>
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On Wed Feb 23 11, Kostik Belousov wrote: > On Wed, Feb 23, 2011 at 01:57:34PM +0000, Alexander Best wrote: > > On Wed Feb 23 11, Kostik Belousov wrote: > > > On Wed, Feb 23, 2011 at 12:56:25PM +0000, John Baldwin wrote: > > > > Author: jhb > > > > Date: Wed Feb 23 12:56:25 2011 > > > > New Revision: 218967 > > > > URL: http://svn.freebsd.org/changeset/base/218967 > > > > > > > > Log: > > > > Fix off-by-one error in check against max_threads_per_proc. > > > > > > > > Submitted by: arundel > > > > MFC after: 1 week > > > > > > > > Modified: > > > > head/sys/kern/kern_thr.c > > > > > > > > Modified: head/sys/kern/kern_thr.c > > > > ============================================================================== > > > > --- head/sys/kern/kern_thr.c Wed Feb 23 10:28:37 2011 (r218966) > > > > +++ head/sys/kern/kern_thr.c Wed Feb 23 12:56:25 2011 (r218967) > > > > @@ -153,7 +153,7 @@ create_thread(struct thread *td, mcontex > > > > p = td->td_proc; > > > > > > > > /* Have race condition but it is cheap. */ > > > > - if (p->p_numthreads >= max_threads_per_proc) { > > > > + if (p->p_numthreads > max_threads_per_proc) { > > > > ++max_threads_hits; > > > > return (EPROCLIM); > > > > } > > > > > > I do not think there was off by one error. The create_thread() function > > > is called to create new thread, and before the process thread counter > > > is incremented in thread_link(). The old test tried to not allow more > > > then max_threads_per_proc threads in a process, now it allows to > > > create max_threads_per_proc. > > > > doesn't the semantics of the term "maximum" imply that it's own value is also > > valid? > > > > if a sign says maximum weight 2000kg, does that mean that a weight of 2000kg is > > invalid and the highest valid weight is 1999,999..kg? > > > > cheers. > > alex > > > > > > > > My guess is that the reference to mentioned pthread_vfork_test failed > > > because reporter set kern.threads.max_threads_per_proc to 100. The > > > test actually tries to create 101 threads, 1 main + 100 new. > > > > so the main process counts as 1 thread and for each pthread_create > > invokation the thread number gets bumped up? > > > > so with a process doing a single pthread_create() that would imply > > this process is having a thread count of 2? > > Exactly. The main thread is the same as all others (almost). thanks for the hint. i wasn't aware of that. however now proctsta -akk also displaying a thread id for a process with no additional threads makes a lot more sense. ;) so in theory: kern.threads.max_threads_per_proc=0 and kern.threads.max_threads_per_proc=1 both forbid a process to trigger any new threads. cheers. alex -- a13x
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