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/*
* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/edp.h>
#include <linux/slab.h>
#include "edp_internal.h"
/*
* This file implements the (1) LRR: least recently requested (2) MRR:
* most recently requested and (3) RR: round robin governors.
*
* Since they are all based on some timestamps, we use a simple list
* (the 'temporal list') for ordering the clients according to the main
* selection criteria. This list is maintained in such a way that
* throttle-victims appear at the tail and promotions are done from the
* head.
*/
static void throttle(struct edp_client *client);
/* Temporal list is manager specific */
static int temporal_start(struct edp_manager *m)
{
struct list_head *head;
struct edp_client *c;
head = kzalloc(sizeof(*head), GFP_KERNEL);
if (!head)
return -ENOMEM;
INIT_LIST_HEAD(head);
m->gov_data = head;
list_for_each_entry(c, &m->clients, link) {
if (req_index(c) < c->e0_index)
list_add(&c->glnk, head);
}
return 0;
}
static void temporal_stop(struct edp_manager *m)
{
kfree(m->gov_data);
m->gov_data = NULL;
}
/*
* We need to remember only those clients that can either be throttled
* or promoted - this way, we have a smaller list.
*/
static void lrr_update_request(struct edp_client *client,
const unsigned int *req)
{
struct list_head *head;
if (req_index(client) < client->e0_index)
list_del(&client->glnk);
edp_default_update_request(client, req, throttle);
if (req_index(client) < client->e0_index) {
head = client->manager->gov_data;
list_add(&client->glnk, head);
}
}
/*
* We need to remember only those clients that can either be throttled
* or promoted - this way, we have a smaller list.
*/
static void mrr_update_request(struct edp_client *client,
const unsigned int *req)
{
struct list_head *head;
if (req_index(client) < client->e0_index)
list_del(&client->glnk);
edp_default_update_request(client, req, throttle);
if (req_index(client) < client->e0_index) {
head = client->manager->gov_data;
list_add_tail(&client->glnk, head);
}
}
static void rr_update_request(struct edp_client *client,
const unsigned int *req)
{
struct list_head *head;
/* new entry */
if (!client->req) {
head = client->manager->gov_data;
list_add(&client->glnk, head);
}
edp_default_update_request(client, req, throttle);
}
static void temporal_promote(struct edp_manager *m)
{
struct list_head *head = m->gov_data;
struct edp_client *c;
unsigned int i;
list_for_each_entry(c, head, glnk) {
if (req_level(c) <= cur_level(c) || !c->notify_promotion)
continue;
i = edp_promotion_point(c, m->remaining);
if (i == cur_index(c))
continue;
m->remaining -= c->states[i] - cur_level(c);
c->cur = c->states + i;
if (c->cur == c->req)
m->num_denied--;
c->notify_promotion(i);
if (!m->remaining || !m->num_denied)
return;
}
}
#define DEFINE_TEMPORAL_GOV(_gov, _name, _func) \
struct edp_governor _gov = { \
.name = _name, \
.owner = THIS_MODULE, \
.start = temporal_start, \
.stop = temporal_stop, \
.update_request = _func, \
.update_loans = edp_default_update_loans, \
.promote = temporal_promote \
};
static DEFINE_TEMPORAL_GOV(lrr_governor, "least_recent", lrr_update_request);
static DEFINE_TEMPORAL_GOV(mrr_governor, "most_recent", mrr_update_request);
static DEFINE_TEMPORAL_GOV(rr_governor, "round_robin", rr_update_request);
static void throttle(struct edp_client *client)
{
struct edp_manager *m = client->manager;
unsigned int required = req_level(client) - cur_level(client);
struct list_head *head = m->gov_data;
struct edp_client *n;
struct edp_client *c;
unsigned int bal;
bal = m->remaining;
n = NULL;
list_for_each_entry_reverse(c, head, glnk) {
if (cur_level(c) > e0_level(c) && c != client) {
c->gwt = edp_throttling_point(c, required - bal);
bal += cur_level(c) - c->states[c->gwt];
n = c;
if (bal >= required)
break;
}
}
c = n;
bal = m->remaining;
if (!c)
goto finish;
/* use the safe version as we might be re-arraging the list */
list_for_each_entry_safe_from(c, n, head, glnk) {
if (cur_level(c) <= e0_level(c) || c == client ||
c->gwt == cur_index(c))
continue;
c->throttle(c->gwt);
bal += cur_level(c) - c->states[c->gwt];
if (c->cur == c->req)
m->num_denied++;
c->cur = c->states + c->gwt;
/* for RR, move this client to the head */
if (m->gov == &rr_governor)
list_move(&c->glnk, head);
if (bal >= required)
break;
}
finish:
m->remaining = bal + cur_level(client);
client->cur = client->states + edp_promotion_point(client, bal);
m->remaining -= cur_level(client);
}
static int __init temporal_init(void)
{
int ret = 0;
int r;
r = edp_register_governor(&lrr_governor);
if (r) {
pr_err("least_recent governor registration failed: %d\n", r);
ret = r;
}
r = edp_register_governor(&mrr_governor);
if (r) {
pr_err("most_recent governor registration failed: %d\n", r);
ret = r;
}
r = edp_register_governor(&rr_governor);
if (r) {
pr_err("round_robin governor registration failed: %d\n", r);
ret = r;
}
return ret;
}
postcore_initcall(temporal_init);
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