Messages in this thread | | | Date | Mon, 20 Jan 2014 13:55:37 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 3/7] numa,sched: build per numa_group active node mask from faults_from statistics |
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On 01/20/2014 11:31 AM, Peter Zijlstra wrote: > On Fri, Jan 17, 2014 at 04:12:05PM -0500, riel@redhat.com wrote: >> /* >> + * Iterate over the nodes from which NUMA hinting faults were triggered, in >> + * other words where the CPUs that incurred NUMA hinting faults are. The >> + * bitmask is used to limit NUMA page migrations, and spread out memory >> + * between the actively used nodes. To prevent flip-flopping, and excessive >> + * page migrations, nodes are added when they cause over 40% of the maximum >> + * number of faults, but only removed when they drop below 20%. >> + */ >> +static void update_numa_active_node_mask(struct task_struct *p) >> +{ >> + unsigned long faults, max_faults = 0; >> + struct numa_group *numa_group = p->numa_group; >> + int nid; >> + >> + for_each_online_node(nid) { >> + faults = numa_group->faults_from[task_faults_idx(nid, 0)] + >> + numa_group->faults_from[task_faults_idx(nid, 1)]; >> + if (faults > max_faults) >> + max_faults = faults; >> + } >> + >> + for_each_online_node(nid) { >> + faults = numa_group->faults_from[task_faults_idx(nid, 0)] + >> + numa_group->faults_from[task_faults_idx(nid, 1)]; >> + if (!node_isset(nid, numa_group->active_nodes)) { >> + if (faults > max_faults * 4 / 10) >> + node_set(nid, numa_group->active_nodes); >> + } else if (faults < max_faults * 2 / 10) >> + node_clear(nid, numa_group->active_nodes); >> + } >> +} > > Why not use 6/16 and 3/16 resp.? That avoids an actual division.
OK, will do.
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