From 4df7df5d61a3ab0a1135d1d7d2b14adb17636e86 Mon Sep 17 00:00:00 2001 From: Grzegorz Wawiorko Date: Fri, 9 Aug 2024 01:14:02 +0200 Subject: [PATCH] New Intel extension cl_intel_subgroup_buffer_prefetch (#1195) --- ...cl_intel_subgroup_buffer_prefetch.asciidoc | 241 ++++++++++++++++++ 1 file changed, 241 insertions(+) create mode 100644 extensions/cl_intel_subgroup_buffer_prefetch.asciidoc diff --git a/extensions/cl_intel_subgroup_buffer_prefetch.asciidoc b/extensions/cl_intel_subgroup_buffer_prefetch.asciidoc new file mode 100644 index 00000000..142bef7c --- /dev/null +++ b/extensions/cl_intel_subgroup_buffer_prefetch.asciidoc @@ -0,0 +1,241 @@ += cl_intel_subgroup_buffer_prefetch + +// This section needs to be after the document title. +:doctype: book +:toc2: +:toc: left +:encoding: utf-8 +:lang: en + +:blank: pass:[ +] + +// Set the default source code type in this document to C, +// for syntax highlighting purposes. +:language: c + +== Name Strings + +`cl_intel_subgroup_buffer_prefetch` + +== Contact + +Grzegorz Wawiorko Intel (grzegorz 'dot' wawiorko 'at' intel 'dot' com) + +== Contributors + +// spell-checker: disable +Grzegorz Wawiorko, Intel + +Ben Ashbaugh, Intel + +Andrzej Ratajewski, Intel + +// spell-checker: enable + +== Notice + +Copyright (c) 2024 Intel Corporation. All rights reserved. + +== Status + +Complete + +== Version + +Built On: {docdate} + +Revision: 1 + +== Dependencies + +OpenCL 1.2 and support for `cl_intel_subgroups` is required. + +This extension requires OpenCL support for SPIR-V, either via OpenCL 2.1 or via the `cl_khr_il_program` extension. + +This extension is written against the OpenCL 3.0 C Language specification, V3.0.16. + +== Overview + +The extension adds the ability to prefetch data from a buffer as a sub-group operation. +The functionality added by this extension can improve the performance of some kernels by prefetching data into a cache, so future reads of the data are from a fast cache rather than slower memory. + +The new block prefetch operations are supported both in the OpenCL C kernel programming language and in the SPIR-V intermediate language. + +The prefetch functions are companions to the sub-group block reads described by the extensions `cl_intel_subgroups`, `cl_intel_subgroups_char`, `cl_intel_subgroups_short` and `cl_intel_subgroups_long`. + + +== New API Functions + +None. + +== New API Enums + +None. + +== New OpenCL C Functions + +Add `uchar` variants of the sub-group block prefetch functions: :: ++ +-- +[source] +---- +void intel_sub_group_block_prefetch_uc( const __global uchar* p ) +void intel_sub_group_block_prefetch_uc2( const __global uchar* p ) +void intel_sub_group_block_prefetch_uc4( const __global uchar* p ) +void intel_sub_group_block_prefetch_uc8( const __global uchar* p ) +void intel_sub_group_block_prefetch_uc16( const __global uchar* p ) +---- +-- + +Add `ushort` variants of the sub-group block prefetch functions: :: ++ +-- +[source] +---- +void intel_sub_group_block_prefetch_us( const __global ushort* p ) +void intel_sub_group_block_prefetch_us2( const __global ushort* p ) +void intel_sub_group_block_prefetch_us4( const __global ushort* p ) +void intel_sub_group_block_prefetch_us8( const __global ushort* p ) +void intel_sub_group_block_prefetch_us16( const __global ushort* p ) +---- +-- + +Add `uint` variants of the sub-group block prefetch functions: :: ++ +-- +[source] +---- +void intel_sub_group_block_prefetch_ui( const __global uint* p ) +void intel_sub_group_block_prefetch_ui2( const __global uint* p ) +void intel_sub_group_block_prefetch_ui4( const __global uint* p ) +void intel_sub_group_block_prefetch_ui8( const __global uint* p ) +---- +-- + +Add `ulong` variants of the sub-group block prefetch functions: :: ++ +-- +[source] +---- +void intel_sub_group_block_prefetch_ul( const __global ulong* p ) +void intel_sub_group_block_prefetch_ul2( const __global ulong* p ) +void intel_sub_group_block_prefetch_ul4( const __global ulong* p ) +void intel_sub_group_block_prefetch_ul8( const __global ulong* p ) +---- +-- + +== Modifications to the OpenCL C Specification + +=== Add a new Section 6.15.X - "Sub-group Prefetch Functions" + +-- +[cols="5a,4",options="header"] +|================================== +|*Function* +|*Description* + +|[source,c] +---- +void intel_sub_group_block_prefetch_uc( + const __global uchar* p ) +void intel_sub_group_block_prefetch_uc2( + const __global uchar* p ) +void intel_sub_group_block_prefetch_uc4( + const __global uchar* p ) +void intel_sub_group_block_prefetch_uc8( + const __global uchar* p ) +void intel_sub_group_block_prefetch_uc16( + const __global uchar* p ) +---- + +| Takes 1, 2, 4, 8 or 16 uchars of data for each work item in the sub-group from the specified pointer as a block operation and saves it in the global cache memory. + +Prefetches have no effect on the behavior of the program but can change its performance characteristics. + +|[source,c] +---- +void intel_sub_group_block_prefetch_us( + const __global ushort* p ) +void intel_sub_group_block_prefetch_us2( + const __global ushort* p ) +void intel_sub_group_block_prefetch_us4( + const __global ushort* p ) +void intel_sub_group_block_prefetch_us8( + const __global ushort* p ) +void intel_sub_group_block_prefetch_us16( + const __global ushort* p ) +---- + +| Takes 1, 2, 4, 8 or 16 ushorts of data for each work item in the sub-group from the specified pointer as a block operation and saves it in the global cache memory. + +Prefetches have no effect on the behavior of the program but can change its performance characteristics. + +|[source,c] +---- +void intel_sub_group_block_prefetch_ui( + const __global uint* p ) +void intel_sub_group_block_prefetch_ui2( + const __global uint* p ) +void intel_sub_group_block_prefetch_ui4( + const __global uint* p ) +void intel_sub_group_block_prefetch_ui8( + const __global uint* p ) +---- + +| Takes 1, 2, 4 or 8 uints of data for each work item in the sub-group from the specified pointer as a block operation and saves it in the global cache memory. + +Prefetches have no effect on the behavior of the program but can change its performance characteristics. + +|[source,c] +---- +void intel_sub_group_block_prefetch_ul( + const __global ulong* p ) +void intel_sub_group_block_prefetch_ul2( + const __global ulong* p ) +void intel_sub_group_block_prefetch_ul4( + const __global ulong* p ) +void intel_sub_group_block_prefetch_ul8( + const __global ulong* p ) +---- + +| Takes 1, 2, 4 or 8 ulongs of data for each work item in the sub-group from the specified pointer as a block operation and saves it in the global cache memory. + +Prefetches have no effect on the behavior of the program but can change its performance characteristics. + +|================================== +-- + +== Modifications to the OpenCL SPIR-V Environment Specification + +=== Add a new section 5.2.X - `cl_intel_subgroup_buffer_prefetch` + +If the OpenCL environment supports the extension `cl_intel_subgroup_buffer_prefetch`, then the environment must accept modules that declare use of the extension `SPV_INTEL_subgroup_buffer_prefetch` via *OpExtension*. + +If the OpenCL environment supports the extension `cl_intel_subgroup_buffer_prefetch` and use of the SPIR-V extension `SPV_INTEL_subgroup_buffer_prefetch` is declared in the module via *OpExtension*, then the environment must accept modules that declare the *SubgroupBufferPrefetchINTEL* capability. + +Note that the restrictions described in Section 7.1.X.3 - _Notes and Restrictions_ in the `cl_intel_spirv_subgroups` extension are unchanged and continue to apply for this extension. + +== Issues + +None. + +//. Issue? +//+ +//-- +//`STATUS`: Description. +//-- + +== Revision History + +[cols="5,15,15,70"] +[grid="rows"] +[options="header"] +|======================================== +|Rev|Date|Author|Changes +|1|2024-06-28|Grzegorz Wawiorko|*First public revision.* +|======================================== + +//************************************************************************ +//Other formatting suggestions: +// +//* Use *bold* text for host APIs, or [source] syntax highlighting. +//* Use `mono` text for device APIs, or [source] syntax highlighting. +//* Use `mono` text for extension names, types, or enum values. +//* Use _italics_ for parameters. +//************************************************************************