|From:||Gilad Ben-Yossef <firstname.lastname@example.org>|
|Subject:||[PATCH v9 0/8] Reduce cross CPU IPI interference|
|Date:||Thu, 9 Feb 2012 10:36:17 +0200|
|Cc:||Gilad Ben-Yossef <email@example.com>|
We have lots of infrastructure in place to partition 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 at times 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 the 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_cond infrastructure API (the former derived from existing arch specific versions in Tile and Arm) and uses them to turn several global IPI invocation to per CPU group invocations. This 9th iteration includes comment clarifications (1st and 4th patches) and folds in a fix from Andrew Morton for macro parameter handling in UP version of on_each_cpu_cond() The patch set also available from the ipi_noise_v9 branch at git://github.com/gby/linux.git Merge notes: during merge, kindly squash the first three patches to avoid bisect failures. The last patch in the series is a review helper only. Please do not merge it. Gilad Ben-Yossef (8): smp: introduce a generic on_each_cpu_mask function arm: move arm over to generic on_each_cpu_mask tile: move tile to use generic on_each_cpu_mask smp: add func to IPI cpus based on parameter func slub: only IPI CPUs that have per cpu obj to flush fs: only send IPI to invalidate LRU BH when needed mm: only IPI CPUs to drain local pages if they exist mm: add vmstat counters for tracking PCP drains arch/arm/kernel/smp_tlb.c | 20 ++------- arch/tile/include/asm/smp.h | 7 --- arch/tile/kernel/smp.c | 19 --------- fs/buffer.c | 15 ++++++- include/linux/smp.h | 47 +++++++++++++++++++++ include/linux/vm_event_item.h | 1 + kernel/smp.c | 91 +++++++++++++++++++++++++++++++++++++++++ mm/page_alloc.c | 45 +++++++++++++++++++- mm/slub.c | 10 ++++- mm/vmstat.c | 2 + 10 files changed, 212 insertions(+), 45 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Copyright © 2012, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds