From 21ba3f485f048c40c3eecf51db313eec79326632 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sat, 11 Aug 2012 16:26:04 -0400
Subject: [PATCH] Be smarter about determining reduction group size.
---
pyopencl/reduction.py | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/pyopencl/reduction.py b/pyopencl/reduction.py
index 9d404a79..68562b11 100644
--- a/pyopencl/reduction.py
+++ b/pyopencl/reduction.py
@@ -158,10 +158,15 @@ def get_reduction_source(
max_work_group_size = device.max_work_group_size
if "RV770" in device.name:
max_work_group_size = 64
- return min(
- max_work_group_size,
- (device.local_mem_size + out_type_size - 1)
- // out_type_size)
+
+ # compute lmem limit
+ from pytools import div_ceil
+ lmem_wg_size = div_ceil(max_work_group_size, out_type_size)
+ result = min(max_work_group_size, lmem_wg_size)
+
+ # round down to power of 2
+ from pyopencl.tools import bitlog2
+ return 2**bitlog2(result)
group_size = min(get_dev_group_size(dev) for dev in devices)
--
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