From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Derr Date: Thu, 25 Sep 2003 13:26:38 +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 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. As pointed by Paul, another reason is the possibility to change on the fly the size/location of cpusets, and the need to apply the change on the attached processes. Thanks a lot for your comments, Simon.