From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shreyas Kejariwal" Subject: Re: SMP questions Date: Thu, 19 Jun 2003 12:55:24 -0400 Sender: linux-smp-owner@vger.kernel.org Message-ID: References: Reply-To: "Shreyas Kejariwal" Return-path: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-smp@vger.kernel.org Thanks Robert. Getting back to Q3, as you mentioned, it uses shared bus. So that makes it hardware specific. However, I read that Posix threads can achieve the same w/o sharing the bus. Is that correct? Can anyone point which dual/SMP processors share memory bus ? Shreyas -- ----------------------------------------------- Shreyas Kejariwal Perigee LLC Tel: 315-453 7842 x 42 "Robert M. Hyatt" wrote in message news:Pine.LNX.4.44.0306191057030.5678-100000@crafty.cis.uab.edu... > On Wed, 18 Jun 2003, Shreyas Kejariwal wrote: > > > Hi everyone, > > > > I am new to this arena and I have few questions so please help me answer > > them. > > > > 1. Looks like most of the new systems employ SMPs. But do we still have > > ASMPs systems ? > > > If you mean "asymmetric multiprocessing" the answer is generally "no". > That has pretty much disappeared. If you mean something like clusters > and so forth, then they are going strong but require different > programming approaches. > > > > > > 2. How can we control the tasks, threads to run on a particular processor ? > > Why would you want to? This is something the operating system should > handle correctly. > > > > Is there a way we can specify ? Take the scenario where there are two > > multi-threaded applications. I want all the threads of the App1 to run on > > Processor, P1 and the threads of the App2 on Processor, P2. Not like some > > threads of App1 would run on P2 depending on the scheduler. > > > > > Most systems support some sort of "processor affinity" stuff, but it is > a bad idea in general. Leave the O/S stuff to the O/S. It _really_ > does know better... > > > > > 3. How can processors access each other's memory / addr space? > > > > Both processors are connected to the memory sub-system with a common > bus. > > > > > 4. Digging into the scheduler code, I found that we can either set scheduler > > policy to be either Round Robin or FIFO. Are there other schedulers > > available which use different policy. > > > > What scheduler are you looking at? > > > > > 5. I read about Shared and Non-shared Cache. How does L2 gets shared. Its on > > the die. So does that mean that you have to buy a shared cache board ? > > > > L2 isn't shared on Intel platforms. Each processor has its own L2 cache > on chip. Otherwise, it is shared just like memory is shared, with a > common bus connecting it to more than one processor. > > > > > > I apologize if some of the questions are stupid and outside the scope of > > this forum. > > > > Moreover, pointers to web-resources would be helpful. > > > > Thanks, > > Shreyas > > > > > > > > > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-smp" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Robert Hyatt Computer and Information Sciences > hyatt@cis.uab.edu University of Alabama at Birmingham > (205) 934-2213 115A Campbell Hall, UAB Station > (205) 934-5473 FAX Birmingham, AL 35294-1170 > > - > To unsubscribe from this list: send the line "unsubscribe linux-smp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >