From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Date: Thu, 25 Sep 2003 16:50:53 +0000 Subject: Re: [Lse-tech] Re: CPUSET Proposal Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Thu, 2003-09-25 at 06:26, Simon Derr wrote: > On Wed, 24 Sep 2003, David Mosberger wrote: > > > BTW: What do cpusets provide that couldn't be done with user-level > > tools on top of the existing sched_setaffinity() system call? > This is a question we had a long in-house debate about. > > The main reason of the inclusion of cpusets *inside* the kernel, is that > we have to deal with applications that may call sched_setaffinity() to > bind their processes to CPUs. Therefore we have to intercept these calls. > We could try to do some LD_PRELOAD userland trick or modify the libc, but > that would not work for statically linked programs. You could also do a big chunk of this by allowing normal privledge users to sched_setaffinity() a *subset* of their current allowed CPU set, but not expand it. sched_setaffinity() isn't *that* old of an interface, so I'm not sure why you can't just change the application at this point. -- Dave Hansen haveblue@us.ibm.com