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scheduler_dynamic: simplify thread balancing logic

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When picking a path to go down with a thread,
conditions unnecessarily piled up.

Instead do it either of two ways:
- move idle threads to main core
- find best core for active threads and move them there

There is no need to worry about cpumask of the thread,
since _find_optimal_core() will always return a core
within the cpumask.

If the found core is the same one as the current,
_move_thread() won't perform any action.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: I0f4782766c15c86b5db0c970cfc9547058845b2a
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/8065
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
This commit is contained in:
Tomasz Zawadzki 2021-05-26 07:12:18 -04:00 committed by Jim Harris
parent 76b7210226
commit 60b655aa91
1 changed files with 4 additions and 12 deletions
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16
lib/event/scheduler_dynamic.c
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@ -194,9 +194,7 @@ balance(struct spdk_scheduler_core_info *cores_info, int cores_count,
{
struct spdk_reactor *reactor;
struct spdk_lw_thread *lw_thread;
struct spdk_thread *thread;
struct spdk_scheduler_core_info *core;
struct spdk_cpuset *cpumask;
struct core_stats *main_core;
uint32_t target_lcore;
uint32_t i, j;
@ -217,19 +215,13 @@ balance(struct spdk_scheduler_core_info *cores_info, int cores_count,
for (j = 0; j < core->threads_count; j++) {
lw_thread = core->threads[j];
thread = spdk_thread_get_from_ctx(lw_thread);
cpumask = spdk_thread_get_cpumask(thread);
load = _get_thread_load(lw_thread);
if (i == g_main_lcore && load >= SCHEDULER_LOAD_LIMIT) {
/* This thread is active and on the main core, we need to pick a core to move it to */
target_lcore = _find_optimal_core(lw_thread);
_move_thread(lw_thread, target_lcore);
} else if (i != g_main_lcore && load < SCHEDULER_LOAD_LIMIT) {
/* This thread is idle but not on the main core, so we need to move it to the main core */
if (load < SCHEDULER_LOAD_LIMIT) {
/* This thread is idle, move it to the main core. */
_move_thread(lw_thread, g_main_lcore);
} else if (i != g_main_lcore && !spdk_cpuset_get_cpu(cpumask, i)) {
/* Move busy thread only if cpumask does not match current core (except main core) */
} else {
/* This thread is active. */
target_lcore = _find_optimal_core(lw_thread);
_move_thread(lw_thread, target_lcore);
}