clear-pkgs-linux-iot-lts2018/0619-drm-i915-gvt-add-a-fas...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhao Yan <yan.y.zhao@intel.com>
Date: Fri, 14 Sep 2018 16:10:20 +0800
Subject: [PATCH] drm/i915/gvt: add a fastpath for cmd parsing on MI_NOOP
MI_NOOP is a common command appearing in almost all command buffers, put it
into a fastpath can improve perfomance, especially in command buffers
contains lots of MI_NOOPs (0s).
Take glmark2 as an example, 3% performance increase is observed after
introduced this patch. Meanwhile, in case where abundant in MI_NOOPs,
up to 12% performance increase is measured.
v2: use lowercase for index of MI_NOOP in cmd_info (zhenyu wang)
Signed-off-by: Li Weinan <weinan.z.li@intel.com>
Signed-off-by: Zhao Yan <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: He, Min <min.he@intel.com>
---
drivers/gpu/drm/i915/gvt/cmd_parser.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
index c22a786..cdccccf 100644
--- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
+++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
@@ -1840,6 +1840,8 @@ static int cmd_handler_mi_batch_buffer_start(struct parser_exec_state *s)
return ret;
}
+static int mi_noop_index;
+
static struct cmd_info cmd_info[] = {
{"MI_NOOP", OP_MI_NOOP, F_LEN_CONST, R_ALL, D_ALL, 0, 1, NULL},
@@ -2525,7 +2527,12 @@ static int cmd_parser_exec(struct parser_exec_state *s)
cmd = cmd_val(s, 0);
- info = get_cmd_info(s->vgpu->gvt, cmd, s->ring_id);
+ /* fastpath for MI_NOOP */
+ if (cmd == MI_NOOP)
+ info = &cmd_info[mi_noop_index];
+ else
+ info = get_cmd_info(s->vgpu->gvt, cmd, s->ring_id);
+
if (info == NULL) {
gvt_vgpu_err("unknown cmd 0x%x, opcode=0x%x, addr_type=%s, ring %d, workload=%p\n",
cmd, get_opcode(cmd, s->ring_id),
@@ -2955,6 +2962,8 @@ static int init_cmd_table(struct intel_gvt *gvt)
kfree(e);
return -EEXIST;
}
+ if (cmd_info[i].opcode == OP_MI_NOOP)
+ mi_noop_index = i;
INIT_HLIST_NODE(&e->hlist);
add_cmd_entry(gvt, e);
--
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