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path: root/drivers/lightnvm/pblk-rl.c
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Diffstat (limited to 'drivers/lightnvm/pblk-rl.c')
-rw-r--r--drivers/lightnvm/pblk-rl.c182
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c
new file mode 100644
index 000000000000..4042162ec9bc
--- /dev/null
+++ b/drivers/lightnvm/pblk-rl.c
@@ -0,0 +1,182 @@
+/*
+ * Copyright (C) 2016 CNEX Labs
+ * Initial release: Javier Gonzalez <javier@cnexlabs.com>
+ * Matias Bjorling <matias@cnexlabs.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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.
+ *
+ * pblk-rl.c - pblk's rate limiter for user I/O
+ *
+ */
+
+#include "pblk.h"
+
+static void pblk_rl_kick_u_timer(struct pblk_rl *rl)
+{
+ mod_timer(&rl->u_timer, jiffies + msecs_to_jiffies(5000));
+}
+
+int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries)
+{
+ int rb_user_cnt = atomic_read(&rl->rb_user_cnt);
+
+ return (!(rb_user_cnt + nr_entries > rl->rb_user_max));
+}
+
+int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries)
+{
+ int rb_gc_cnt = atomic_read(&rl->rb_gc_cnt);
+ int rb_user_active;
+
+ /* If there is no user I/O let GC take over space on the write buffer */
+ rb_user_active = READ_ONCE(rl->rb_user_active);
+ return (!(rb_gc_cnt + nr_entries > rl->rb_gc_max && rb_user_active));
+}
+
+void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries)
+{
+ atomic_add(nr_entries, &rl->rb_user_cnt);
+
+ /* Release user I/O state. Protect from GC */
+ smp_store_release(&rl->rb_user_active, 1);
+ pblk_rl_kick_u_timer(rl);
+}
+
+void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries)
+{
+ atomic_add(nr_entries, &rl->rb_gc_cnt);
+}
+
+void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc)
+{
+ atomic_sub(nr_user, &rl->rb_user_cnt);
+ atomic_sub(nr_gc, &rl->rb_gc_cnt);
+}
+
+unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl)
+{
+ return atomic_read(&rl->free_blocks);
+}
+
+/*
+ * We check for (i) the number of free blocks in the current LUN and (ii) the
+ * total number of free blocks in the pblk instance. This is to even out the
+ * number of free blocks on each LUN when GC kicks in.
+ *
+ * Only the total number of free blocks is used to configure the rate limiter.
+ */
+static int pblk_rl_update_rates(struct pblk_rl *rl, unsigned long max)
+{
+ unsigned long free_blocks = pblk_rl_nr_free_blks(rl);
+
+ if (free_blocks >= rl->high) {
+ rl->rb_user_max = max - rl->rb_gc_rsv;
+ rl->rb_gc_max = rl->rb_gc_rsv;
+ rl->rb_state = PBLK_RL_HIGH;
+ } else if (free_blocks < rl->high) {
+ int shift = rl->high_pw - rl->rb_windows_pw;
+ int user_windows = free_blocks >> shift;
+ int user_max = user_windows << PBLK_MAX_REQ_ADDRS_PW;
+ int gc_max;
+
+ rl->rb_user_max = user_max;
+ gc_max = max - rl->rb_user_max;
+ rl->rb_gc_max = max(gc_max, rl->rb_gc_rsv);
+
+ if (free_blocks > rl->low)
+ rl->rb_state = PBLK_RL_MID;
+ else
+ rl->rb_state = PBLK_RL_LOW;
+ }
+
+ return rl->rb_state;
+}
+
+void pblk_rl_set_gc_rsc(struct pblk_rl *rl, int rsv)
+{
+ rl->rb_gc_rsv = rl->rb_gc_max = rsv;
+}
+
+void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line)
+{
+ struct pblk *pblk = container_of(rl, struct pblk, rl);
+ int ret;
+
+ atomic_add(line->blk_in_line, &rl->free_blocks);
+ /* Rates will not change that often - no need to lock update */
+ ret = pblk_rl_update_rates(rl, rl->rb_budget);
+
+ if (ret == (PBLK_RL_MID | PBLK_RL_LOW))
+ pblk_gc_should_start(pblk);
+ else
+ pblk_gc_should_stop(pblk);
+}
+
+void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line)
+{
+ struct pblk *pblk = container_of(rl, struct pblk, rl);
+ int ret;
+
+ atomic_sub(line->blk_in_line, &rl->free_blocks);
+
+ /* Rates will not change that often - no need to lock update */
+ ret = pblk_rl_update_rates(rl, rl->rb_budget);
+ if (ret == (PBLK_RL_MID | PBLK_RL_LOW))
+ pblk_gc_should_start(pblk);
+ else
+ pblk_gc_should_stop(pblk);
+}
+
+int pblk_rl_gc_thrs(struct pblk_rl *rl)
+{
+ return rl->high;
+}
+
+int pblk_rl_sysfs_rate_show(struct pblk_rl *rl)
+{
+ return rl->rb_user_max;
+}
+
+static void pblk_rl_u_timer(unsigned long data)
+{
+ struct pblk_rl *rl = (struct pblk_rl *)data;
+
+ /* Release user I/O state. Protect from GC */
+ smp_store_release(&rl->rb_user_active, 0);
+}
+
+void pblk_rl_free(struct pblk_rl *rl)
+{
+ del_timer(&rl->u_timer);
+}
+
+void pblk_rl_init(struct pblk_rl *rl, int budget)
+{
+ unsigned int rb_windows;
+
+ rl->high = rl->total_blocks / PBLK_USER_HIGH_THRS;
+ rl->low = rl->total_blocks / PBLK_USER_LOW_THRS;
+ rl->high_pw = get_count_order(rl->high);
+
+ /* This will always be a power-of-2 */
+ rb_windows = budget / PBLK_MAX_REQ_ADDRS;
+ rl->rb_windows_pw = get_count_order(rb_windows) + 1;
+
+ /* To start with, all buffer is available to user I/O writers */
+ rl->rb_budget = budget;
+ rl->rb_user_max = budget;
+ atomic_set(&rl->rb_user_cnt, 0);
+ rl->rb_gc_max = 0;
+ rl->rb_state = PBLK_RL_HIGH;
+ atomic_set(&rl->rb_gc_cnt, 0);
+
+ setup_timer(&rl->u_timer, pblk_rl_u_timer, (unsigned long)rl);
+ rl->rb_user_active = 0;
+}