> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > owner@xxxxxxxxxxxxxxx] On Behalf Of raz ben yehuda > Sent: Wednesday, August 26, 2009 10:54 AM > To: Maxim Levitsky > Cc: Christoph Lameter; Peter Zijlstra; Chris Friesen; Mike Galbraith; > riel@xxxxxxxxxx; mingo@xxxxxxx; andrew motron; wiseman@xxxxxxxxxxxxxx; > lkml; linux-rt-users@xxxxxxxxxxxxxxx > Subject: Re: RFC: THE OFFLINE SCHEDULER > > > On Wed, 2009-08-26 at 17:45 +0300, Maxim Levitsky wrote: > > On Wed, 2009-08-26 at 09:47 -0400, Christoph Lameter wrote: > > > On Wed, 26 Aug 2009, raz ben yehuda wrote: > > > > > > > How will the kernel is going to handle 32 processors machines ? > These > > > > numbers are no longer a science-fiction. > > > > > > The kernel is already running on 4096 processor machines. Dont worry > about > > > that. > > > > > > > What i am suggesting is merely a different approach of how to handle > > > > multiple core systems. instead of thinking in processes, threads and > so > > > > on i am thinking in services. Why not take a processor and define > this > > > > processor to do just firewalling ? encryption ? routing ? > transmission ? > > > > video processing... and so on... > > > > > > I think that is a valuable avenue to explore. What we do so far is > > > treating each processor equally. Dedicating a processor has benefits > in > > > terms of cache hotness and limits OS noise. > > > > > > Most of the large processor configurations already partition the > system > > > using cpusets in order to limit the disturbance by OS processing. A > set of > > > cpus is used for OS activities and system daemons are put into that > set. > > > But what can be done is limited because the OS threads as well as > > > interrupt and timer processing etc cannot currently be moved. The > ideas > > > that you are proposing are particularly usedful for applications that > > > require low latencies and cannot tolerate OS noise easily (Infiniband > MPI > > > base jobs f.e.) > > > > My 0.2 cents: > > > > I have always been fascinated by the idea of controlling another cpu > > from the main CPU. > > > > Usually these cpus are custom, run proprietary software, and have no > > datasheet on their I/O interfaces. > > > > But, being able to turn an ordinary CPU into something like that seems > > to be very nice. > > > > For example, It might help with profiling. Think about a program that > > can run uninterrupted how much it wants. > > > > I might even be better, if the dedicated CPU would use a predefined > > reserved memory range (I wish there was a way to actually lock it to > > that range) > > > > On the other hand, I could see this as a jump platform for more > > proprietary code, something like that: we use linux in out server > > platform, but out "insert buzzword here" network stack pro+ can handle > > 100% more load that linux does, and it runs on a dedicated core.... > > > > In the other words, we might see 'firmwares' that take an entire cpu for > > their usage. > This is exactly what offsched (sos) is. you got it. SOS was partly > inspired by the notion of a GPU. > Processors are to become more and more redundant and Linux as an > evolutionary system must use it. why not offload raid5 write engine ? > why not encrypt in a different processor ? RAID/Encryption + GPU. You got it. This is what one of our teams did but by offloading it on a PCIe I/O module and using couple(Protocol+Application core) of cores. One core could run SAS/SATA and other could run your home grown application f/w and/or a linux distro and you could make it do whatever you want. But that was then. Multi-Core systems are now a commodity. Chetan Loke -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
