Date: Wed, 26 Mar 2003 00:53:59 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: alex@dynaweb.ru Cc: FreeBSD hackers list <freebsd-hackers@freebsd.org> Subject: Re: Some specific questions about 5.x Message-ID: <3E816AA7.1B6A02C@mindspring.com> References: <3E815D53.6010404@dynaweb.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
Alex wrote: > I was so much enthusiastic about kernel threads implemented in 5.x but > some ugly rumors spoiled my dreams :0) > So I want to get if these rumors are myths or not. 5.x does not implement traditional "kernel threads" like you appear to be thinking about them. Instead, it implements a variation of scheduler activations. Traditional "kernel threads" have a lot of unnecessary overhead problems, including CPU affinity and thread group negaffinity, necessary for increased single application concurrency. See the KSE documentation for more information. > 1. Is it true that kernel threads are more "heavy" than userspace > ones (pthread) and hence application with hundreds of threads will work > evidently slower than that using pthreads due to more switching penalties? Yes and No. See the KSE documentation for more information. > 2. Is it true that even 5.x has no implementation for inter-process > semaphores that are blocking calling thread only not the whole process > as usually in FreeBSD? No, for values of x > 0. See the KSE documentation for more information. -- Terry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3E816AA7.1B6A02C>