From 76ff480ec9633d689a14e15bc0e3d10a84e6853b Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 18 Aug 2016 17:17:17 +0100
Subject: [PATCH] drm/i915/cmdparser: Use binary search for faster register
lookup
A significant proportion of the cmdparsing time for some batches is the
cost to find the register in the mmiotable. We ensure that those tables
are in ascending order such that we could do a binary search if it was
ever merited. It is.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-38-chris@chris-wilson.co.uk
---
drivers/gpu/drm/i915/i915_cmd_parser.c | 42 ++++++++++++--------------
1 file changed, 20 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index 690aaf51d715..e128e3ab8452 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -921,36 +921,37 @@ find_cmd(struct intel_engine_cs *engine,
}
static const struct drm_i915_reg_descriptor *
-find_reg(const struct drm_i915_reg_descriptor *table,
- int count, u32 addr)
+__find_reg(const struct drm_i915_reg_descriptor *table, int count, u32 addr)
{
- int i;
-
- for (i = 0; i < count; i++) {
- if (i915_mmio_reg_offset(table[i].addr) == addr)
- return &table[i];
+ int start = 0, end = count;
+ while (start < end) {
+ int mid = start + (end - start) / 2;
+ int ret = addr - i915_mmio_reg_offset(table[mid].addr);
+ if (ret < 0)
+ end = mid;
+ else if (ret > 0)
+ start = mid + 1;
+ else
+ return &table[mid];
}
-
return NULL;
}
static const struct drm_i915_reg_descriptor *
-find_reg_in_tables(const struct drm_i915_reg_table *tables,
- int count, bool is_master, u32 addr)
+find_reg(const struct intel_engine_cs *engine, bool is_master, u32 addr)
{
- int i;
- const struct drm_i915_reg_table *table;
- const struct drm_i915_reg_descriptor *reg;
+ const struct drm_i915_reg_table *table = engine->reg_tables;
+ int count = engine->reg_table_count;
- for (i = 0; i < count; i++) {
- table = &tables[i];
+ do {
if (!table->master || is_master) {
- reg = find_reg(table->regs, table->num_regs,
- addr);
+ const struct drm_i915_reg_descriptor *reg;
+
+ reg = __find_reg(table->regs, table->num_regs, addr);
if (reg != NULL)
return reg;
}
- }
+ } while (table++, --count);
return NULL;
}
@@ -1073,10 +1074,7 @@ static bool check_cmd(const struct intel_engine_cs *engine,
offset += step) {
const u32 reg_addr = cmd[offset] & desc->reg.mask;
const struct drm_i915_reg_descriptor *reg =
- find_reg_in_tables(engine->reg_tables,
- engine->reg_table_count,
- is_master,
- reg_addr);
+ find_reg(engine, is_master, reg_addr);
if (!reg) {
DRM_DEBUG_DRIVER("CMD: Rejected register 0x%08X in command: 0x%08X (exec_id=%d)\n",
--
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