On Sat, Nov 18, 2006 at 01:17:42PM +0000, [EMAIL PROTECTED] wrote: > Antonio Vargas <[EMAIL PROTECTED]> wrote: > > Linux-only doesn't exist per-se, since linux is GPL and any GPL code > > can be remixed without problems. So, the question would be if it's ok > > to remix GPL with DFBSD license (which probably doesn't) > > Indeed you are right, RCU patent has been licensed by IBM to use in GPL code > only. Hence any GPL OS can use it, but the BSDs certainly cannot, and no more > Solaris. In practice, only Linux can make use of it, which was obviously IBM > intent. Note this is a patent question, not a copyright question so you > cannot work around it by rewriting it. To check that, i have googled a little > bit and found some comments by proeminent Linux developers who were not very
There'a lot of discussion about a lot of things. RCU has done pretty spectactularly for that community overall. > convinced of the performance gain associated with RCU. Of course the reads are > lockless, but from time to time you have to update, and the penality is heavy. The penalty is no more than the typical cache issues you have with invalidating cache data. > Once more, Solaris succeeds in having very good SMP scalability and > excellent threading behavior without using any of these tricks. > Fine grained locking needs a lot of polishing to work fine, but when > everything is in good shape, it works. Lock aren't free and a long chain of a locks are going to create other kind of problems. Generally you have a mixture of a shallow lock hierarchy and per CPU storage to localize those accesses. It's the Linux philisophy and it has worked out well. The contention stats I've gathered from that kernel support that conclusion and is a testimony about how successful their techniques are. bill
