On 1/8/2012 11:26 AM, Gilad Ben-Yossef wrote: > We have lots of infrastructure in place to partition a multi-core systems > such that we have a group of CPUs that are dedicated to specific task: > cgroups, scheduler and interrupt affinity and cpuisol boot parameter. > Still, kernel code will some time interrupt all CPUs in the system via IPIs > for various needs. These IPIs are useful and cannot be avoided altogether, > but in certain cases it is possible to interrupt only specific CPUs that > have useful work to do and not the entire system. > > This patch set, inspired by discussions with Peter Zijlstra and Frederic > Weisbecker when testing the nohz task patch set, is a first stab at trying > to explore doing this by locating the places where such global IPI calls > are being made and turning a global IPI into an IPI for a specific group > of CPUs. The purpose of the patch set is to get feedback if this is the > right way to go for dealing with this issue and indeed, if the issue is > even worth dealing with at all. Based on the feedback from this patch set > I plan to offer further patches that address similar issue in other code > paths. > > The patch creates an on_each_cpu_mask and on_each_cpu_conf infrastructure > API (the former derived from existing arch specific versions in Tile and > Arm) and and uses them to turn several global IPI invocation to per CPU > group invocations. Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxx> (To be fair, mostly this acks the proposed infrastructure, and moving the functions out of the tile architecture and into the generic code; I not expert enough at slub or the invalidate_bh_lrus path to ack those changes, other than to say I like how they look.) -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>