Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759229AbcDAPSY (ORCPT ); Fri, 1 Apr 2016 11:18:24 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:35310 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752360AbcDAPSW (ORCPT ); Fri, 1 Apr 2016 11:18:22 -0400 From: Luca Abeni To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Luca Abeni Subject: [RFC v2 0/7] CPU reclaiming for SCHED_DEADLINE Date: Fri, 1 Apr 2016 17:12:26 +0200 Message-Id: <1459523553-29089-1-git-send-email-luca.abeni@unitn.it> X-Mailer: git-send-email 2.5.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2404 Lines: 57 Hi all, this patchset implements CPU reclaiming (using the GRUB algorithm[1]) for SCHED_DEADLINE: basically, this feature allows SCHED_DEADLINE tasks to consume more than their reserved runtime, up to a maximum fraction of the CPU time (so that other tasks are left some spare CPU time to execute), if this does not break the guarantees of other SCHED_DEADLINE tasks. The patchset applies on top of tip/master. Respect to the first version of the RFC: - I tried to address all the comments I received - I removed some patches that were not really used in the patchset - I rebased on tip/master - I removed all the checkpatch warnings - I added a new patch (patch 0004) to update the total -deadline utilization (dl_b->total_bw) at the correct time, addressing the large comment in __setparam_dl() (see both dl_overflow() and __setparam_dl()). The implemented CPU reclaiming algorithm is based on tracking the utilization U_act of active tasks (first 3 patches), and modifying the runtime accounting rule (see patch 0005). The original GRUB algorithm is modified as described in [2] to support multiple CPUs (the original algorithm only considered one single CPU, this one tracks U_act per runqueue) and to leave an "unreclaimable" fraction of CPU time to non SCHED_DEADLINE tasks (the original algorithm can consume 100% of the CPU time, starving all the other tasks). I tried to split the patches so that the whole patchset can be better understood; if they should be organized in a different way, let me know. The first 3 patches (tracking of per-runqueue active utilization) can be useful for frequency scaling too. Patches 0005-0007 implement the reclaiming algorithm. and patch 0004 uses the newly introduced "inactive timer" (introduced in patch 0003) to fix dl_overflow() and __setparam_dl(). Luca Abeni (7): Track the active utilisation Correctly track the active utilisation for migrating tasks Improve the tracking of active utilisation Fix the update of the total -deadline utilization GRUB accounting Make GRUB a task's flag Do not reclaim the whole CPU bandwidth include/linux/sched.h | 1 + include/uapi/linux/sched.h | 1 + kernel/sched/core.c | 44 ++++----- kernel/sched/deadline.c | 225 +++++++++++++++++++++++++++++++++++++++++---- kernel/sched/sched.h | 13 +++ 5 files changed, 239 insertions(+), 45 deletions(-) -- 2.5.0