From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Date: Fri, 23 Jul 2004 03:27:24 +0000 Subject: Re: [RFC] Patch for isolated scheduler domains Message-Id: <4100859C.9060409@yahoo.com.au> List-Id: References: <20040722164126.GB13189@sgi.com> <20040722175459.GA30059@elte.hu> In-Reply-To: <20040722175459.GA30059@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar Cc: Dimitri Sivanich , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Dimitri Sivanich wrote: > > >>I'm interested in implementing something I'll call isolated sched >>domains for single cpus (to minimize the latencies involved when doing >>things like load balancing on certain select cpus) on IA64. >> >>Below I've included an initial patch to illustrate what I'd like to >>do. I know there's been mention of 'platform specific work' in the >>area of sched domains. This patch only addresses IA64, but could be >>made generic as well. The code is derived directly from the current >>default arch_init_sched_domains code. > > > it looks good to me - and i'd suggest to put it into sched.c. Every > architecture benefits from the ability to define isolated CPUs. > Cool. Have you actually tried running it? With Ingo's correction, it should work fine but I don't think anyone has tested this. > One minor nit wrt. this line: > > + cpu_sd->flags &= ~(SD_BALANCE_NEWIDLE | SD_BALANCE_EXEC | > + SD_BALANCE_CLONE); /* Probably redundant */ > > i'd suggest to set it to 0. You dont want WAKE_AFFINE nor WAKE_BALANCE > to move your tasks out of the isolated domain. > > >>- Assuming boot time configuration is appropriate ('isolcpus=' in my example), >> is allowing boot time configuration of only completely isolated cpus >> focusing too narrowly on this one concept, or should a boot time >> configuration allow for a broader array of configurations, or would other >> types of sched domain configurations be addressed separately? > > > i'd prefer to go with this simple solution and wait for actual usage > patterns to materialize. If it becomes popular we can define a syscall > to configure the domain hierarchy (maybe even the parameters) runtime. > Seconded.