From: Yamin Friedman <yaminf@xxxxxxxxxxxx>
blk_dim implements a different algorithm than net_dim that is optimized for nvmf
storage applications.
The algorithm optimizes for number of completions and ratio between completions
and events.
It also has a feature for fast reduction of moderation level when the traffic
changes in such a way as to no longer require high moderation in order to avoid
long latencies.
blk_dim.h will be called from the ib_core module.
Signed-off-by: Yamin Friedman <yaminf@xxxxxxxxxxxx>
Signed-off-by: Tal Gilboa <talgi@xxxxxxxxxxxx>
---
MAINTAINERS | 1 +
include/linux/blk_dim.h | 56 ++++++++++++++++++++
lib/dim/Makefile | 7 ++-
lib/dim/blk_dim.c | 114 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 177 insertions(+), 1 deletion(-)
create mode 100644 include/linux/blk_dim.h
create mode 100644 lib/dim/blk_dim.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 6ae949be8b83..2860a3316be5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5337,6 +5337,7 @@ DYNAMIC INTERRUPT MODERATION
M: Tal Gilboa <talgi@xxxxxxxxxxxx>
S: Maintained
F: include/linux/net_dim.h
+F: include/linux/blk_dim.h
F: include/linux/dim.h
F: lib/dim/
diff --git a/include/linux/blk_dim.h b/include/linux/blk_dim.h
new file mode 100644
index 000000000000..a044f62ec8fe
--- /dev/null
+++ b/include/linux/blk_dim.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef BLK_DIM_H
+#define BLK_DIM_H
+
+#include <linux/module.h>
+#include <linux/dim.h>
+
+#define BLK_DIM_PARAMS_NUM_PROFILES 8
+#define BLK_DIM_START_PROFILE 0
+
+static const struct dim_cq_moder
+blk_dim_prof[BLK_DIM_PARAMS_NUM_PROFILES] = {
+ {1, 0, 1, 0},
+ {2, 0, 2, 0},
+ {4, 0, 4, 0},
+ {16, 0, 4, 0},
+ {32, 0, 4, 0},
+ {32, 0, 16, 0},
+ {256, 0, 16, 0},
+ {256, 0, 32, 0},
+};
+
+void blk_dim(struct dim *dim, struct dim_sample end_sample);
+
+#endif /* BLK_DIM_H */
diff --git a/lib/dim/Makefile b/lib/dim/Makefile
index 160afe288df0..2b3c57318dbb 100644
--- a/lib/dim/Makefile
+++ b/lib/dim/Makefile
@@ -2,8 +2,13 @@
# DIM Dynamic Interrupt Moderation library
#
-obj-$(CONFIG_DIMLIB) = net_dim.o
+obj-$(CONFIG_DIMLIB) += net_dim.o
+obj-$(CONFIG_DIMLIB) += blk_dim.o
net_dim-y = \
dim.o \
net_dim.o
+
+blk_dim-y = \
+ dim.o \
+ blk_dim.o
diff --git a/lib/dim/blk_dim.c b/lib/dim/blk_dim.c
new file mode 100644
index 000000000000..49107c169b56
--- /dev/null
+++ b/lib/dim/blk_dim.c
@@ -0,0 +1,114 @@
+#include <linux/blk_dim.h>
+
+static inline int blk_dim_step(struct dim *dim)
+{
+ switch (dim->tune_state) {
+ case DIM_PARKING_ON_TOP:
+ case DIM_PARKING_TIRED:
+ break;
+ case DIM_GOING_RIGHT:
+ if (dim->profile_ix == (BLK_DIM_PARAMS_NUM_PROFILES - 1))
+ return DIM_ON_EDGE;
+ dim->profile_ix++;
+ dim->steps_right++;
+ break;
+ case DIM_GOING_LEFT:
+ if (dim->profile_ix == 0)
+ return DIM_ON_EDGE;
+ dim->profile_ix--;
+ dim->steps_left++;
+ break;
+ }
+
+ return DIM_STEPPED;
+}
+
+static inline int blk_dim_stats_compare(struct dim_stats *curr, struct dim_stats *prev)
+{
+ /* first stat */
+ if (!prev->cpms)
+ return DIM_STATS_SAME;
+
+ if (IS_SIGNIFICANT_DIFF(curr->cpms, prev->cpms))
+ return (curr->cpms > prev->cpms) ? DIM_STATS_BETTER :
+ DIM_STATS_WORSE;
+
+ if (IS_SIGNIFICANT_DIFF(curr->cpe_ratio, prev->cpe_ratio))
+ return (curr->cpe_ratio > prev->cpe_ratio) ? DIM_STATS_BETTER :
+ DIM_STATS_WORSE;
+
+ return DIM_STATS_SAME;
+}
+
+static inline bool blk_dim_decision(struct dim_stats *curr_stats, struct dim *dim)
+{
+ int prev_ix = dim->profile_ix;
+ int stats_res;
+ int step_res;
+
+ switch (dim->tune_state) {
+ case DIM_PARKING_ON_TOP:
+ break;
+ case DIM_PARKING_TIRED:
+ break;
+
+ case DIM_GOING_RIGHT:
+ case DIM_GOING_LEFT:
+ stats_res = blk_dim_stats_compare(curr_stats, &dim->prev_stats);
+
+ switch (stats_res) {
+ case DIM_STATS_SAME:
+ if (curr_stats->cpe_ratio <= 50*prev_ix)
+ dim->profile_ix = 0;
+ break;
+ case DIM_STATS_WORSE:
+ dim_turn(dim);
+ default:
+ case DIM_STATS_BETTER:
+ /* fall through */
+ step_res = blk_dim_step(dim);
+ if (step_res == DIM_ON_EDGE)
+ dim_turn(dim);
+ break;
+ }
+ break;
+ }
+
+ dim->prev_stats = *curr_stats;
+
+ return dim->profile_ix != prev_ix;
+}
+
+void blk_dim(struct dim *dim, struct dim_sample end_sample)
+{
+ struct dim_stats curr_stats;
+ u16 nevents;
+
+ switch (dim->state) {
+ case DIM_MEASURE_IN_PROGRESS:
+ nevents = end_sample.event_ctr - dim->start_sample.event_ctr;
+ if (nevents < DIM_NEVENTS) {
+ dim_create_sample(end_sample.event_ctr, end_sample.pkt_ctr,
+ end_sample.byte_ctr, end_sample.comp_ctr, &dim->measuring_sample);
+ break;
+ }
+ dim_calc_stats(&dim->start_sample, &end_sample,
+ &curr_stats);
+ if (blk_dim_decision(&curr_stats, dim)) {
+ dim->state = DIM_APPLY_NEW_PROFILE;
+ schedule_work(&dim->work);
+ break;
+ }
+ /* fall through */
+ case DIM_START_MEASURE:
+ dim->state = DIM_MEASURE_IN_PROGRESS;
+ dim_create_sample(end_sample.event_ctr, end_sample.pkt_ctr, end_sample.byte_ctr,
+ end_sample.comp_ctr, &dim->start_sample);
+ dim_create_sample(end_sample.event_ctr, end_sample.pkt_ctr, end_sample.byte_ctr,
+ end_sample.comp_ctr, &dim->measuring_sample);
+ break;
+ case DIM_APPLY_NEW_PROFILE:
+ break;
+ }
+}
+EXPORT_SYMBOL(blk_dim);
--
2.19.1
