From 29f26f72c96b69784d896145a6406064cda0dac7 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Mon, 8 Aug 2011 17:44:19 +0200
Subject: [PATCH] Avoid lmem bank conflicts only on hardware sporting real
lmem.
---
loopy/codegen/prefetch.py | 70 +++++++++++++++++++++++----------------
1 file changed, 41 insertions(+), 29 deletions(-)
diff --git a/loopy/codegen/prefetch.py b/loopy/codegen/prefetch.py
index bec065c9a..53bb1766f 100644
--- a/loopy/codegen/prefetch.py
+++ b/loopy/codegen/prefetch.py
@@ -1,6 +1,7 @@
from __future__ import division
from pytools import Record
+import pyopencl as cl
import pyopencl.characterize as cl_char
from loopy.codegen import wrap_in, gen_code_block
@@ -30,36 +31,47 @@ def preprocess_prefetch(kernel):
other_dim_sizes = (pf.itemsize
* product(dim_storage_lengths[:-1]))
- min_mult = cl_char.local_memory_bank_count(kernel.device)
- good_incr = None
- new_dsl = dim_storage_lengths
- min_why_not = None
-
- for increment in range(dim_storage_lengths[-1]//2):
-
- test_dsl = dim_storage_lengths[:]
- test_dsl[-1] = test_dsl[-1] + increment
- new_mult, why_not = cl_char.why_not_local_access_conflict_free(
- kernel.device, pf.itemsize,
- shape, test_dsl)
-
- # will choose smallest increment 'automatically'
- if new_mult < min_mult:
- new_lmem_use = other_pf_sizes + pf.itemsize*product(new_dsl)
- if new_lmem_use < lmem_size:
- new_dsl = test_dsl
- min_mult = new_mult
- min_why_not = why_not
- good_incr = increment
-
- if min_mult != 1:
+ if kernel.device.local_mem_type == cl.device_local_mem_type.GLOBAL:
+ # FIXME: could try to avoid cache associativity disasters
+ new_dsl = dim_storage_lengths
+
+ elif kernel.device.local_mem_type == cl.device_local_mem_type.LOCAL:
+ min_mult = cl_char.local_memory_bank_count(kernel.device)
+ good_incr = None
+ new_dsl = dim_storage_lengths
+ min_why_not = None
+
+ for increment in range(dim_storage_lengths[-1]//2):
+
+ test_dsl = dim_storage_lengths[:]
+ test_dsl[-1] = test_dsl[-1] + increment
+ new_mult, why_not = cl_char.why_not_local_access_conflict_free(
+ kernel.device, pf.itemsize,
+ shape, test_dsl)
+
+ # will choose smallest increment 'automatically'
+ if new_mult < min_mult:
+ new_lmem_use = other_pf_sizes + pf.itemsize*product(new_dsl)
+ if new_lmem_use < lmem_size:
+ new_dsl = test_dsl
+ min_mult = new_mult
+ min_why_not = why_not
+ good_incr = increment
+
+ if min_mult != 1:
+ from warnings import warn
+ from loopy import LoopyAdvisory
+ warn("could not find a conflict-free mem layout "
+ "for prefetch of '%s' "
+ "(currently: %dx conflict, increment: %d, reason: %s)"
+ % (pf.input_vector, min_mult, good_incr, min_why_not),
+ LoopyAdvisory)
+ else:
from warnings import warn
- from loopy import LoopyAdvisory
- warn("could not find a conflict-free mem layout "
- "for prefetch of '%s' "
- "(currently: %dx conflict, increment: %d, reason: %s)"
- % (pf.input_vector, min_mult, good_incr, min_why_not),
- LoopyAdvisory)
+ warn("unknown type of local memory")
+
+ new_dsl = dim_storage_lengths
+
new_pf = pf.copy(dim_storage_lengths=new_dsl,
name="prefetch_%s_%d" % (pf.input_vector, i_pf))
--
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