From: Tobias Burnus <tobias@codesourcery.com>
To: Andrew Stubbs <ams@codesourcery.com>, <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH 08/17] openmp: -foffload-memory=pinned
Date: Thu, 7 Jul 2022 13:54:09 +0200 [thread overview]
Message-ID: <bcd0309d-7cce-3ced-4170-5ffe2ac405ac@codesourcery.com> (raw)
In-Reply-To: <8011a994bb38db60f37127880b0fc682564f6e8d.1657188329.git.ams@codesourcery.com>
Hi Andrew,
On 07.07.22 12:34, Andrew Stubbs wrote:
> Implement the -foffload-memory=pinned option such that libgomp is
> instructed to enable fully-pinned memory at start-up. The option is
> intended to provide a performance boost to certain offload programs without
> modifying the code.
...
> gcc/ChangeLog:
>
> * omp-builtins.def (BUILT_IN_GOMP_ENABLE_PINNED_MODE): New.
> * omp-low.cc (omp_enable_pinned_mode): New function.
> (execute_lower_omp): Call omp_enable_pinned_mode.
>
> libgomp/ChangeLog:
>
> * config/linux/allocator.c (always_pinned_mode): New variable.
> (GOMP_enable_pinned_mode): New function.
> (linux_memspace_alloc): Disable pinning when always_pinned_mode set.
> (linux_memspace_calloc): Likewise.
> (linux_memspace_free): Likewise.
> (linux_memspace_realloc): Likewise.
> * libgomp.map: Add GOMP_enable_pinned_mode.
> * testsuite/libgomp.c/alloc-pinned-7.c: New test.
> ...
...
> --- a/gcc/omp-low.cc
> +++ b/gcc/omp-low.cc
> @@ -14620,6 +14620,68 @@ lower_omp (gimple_seq *body, omp_context *ctx)
> input_location = saved_location;
> }
>
> +/* Emit a constructor function to enable -foffload-memory=pinned
> + at runtime. Libgomp handles the OS mode setting, but we need to trigger
> + it by calling GOMP_enable_pinned mode before the program proper runs. */
> +
> +static void
> +omp_enable_pinned_mode ()
Is there a reason not to use the mechanism of OpenMP's 'requires'
directive for this?
(Okay, I have to admit that the final patch was only committed on
Monday. But still ...)
It looks very similar in spirit. I don't know whether there are issues
of having -foffload-memory=pinned in some TU and not, but that could be
handled in a similar way to GOMP_REQUIRES_TARGET_USED.
For requires, omp_requires_mask is streamed out if
OMP_REQUIRES_TARGET_USED and g->have_offload. (For completeness, it also
requires ENABLE_OFFLOADING.)
This data is read in by all lto1 (in lto-cgraph.cc) and checked for
consistency. This data is then also passed on to *mkoffload.cc.
And in libgomp, it is processed by GOMP_register_ver.
Likewise, the 'requires' mechanism could then also be used in '[PATCH
16/17] amdgcn, openmp: Auto-detect USM mode and set HSA_XNACK'.
Tobias
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next prev parent reply other threads:[~2022-07-07 11:54 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 10:34 [PATCH 00/17] openmp, nvptx, amdgcn: 5.0 Memory Allocators Andrew Stubbs
2022-07-07 10:34 ` [PATCH 01/17] libgomp, nvptx: low-latency memory allocator Andrew Stubbs
2022-12-08 11:40 ` Jakub Jelinek
2022-07-07 10:34 ` [PATCH 02/17] libgomp: pinned memory Andrew Stubbs
2022-12-08 12:11 ` Jakub Jelinek
2022-12-08 12:51 ` Andrew Stubbs
2022-12-08 14:02 ` Tobias Burnus
2022-12-08 14:35 ` Andrew Stubbs
2022-12-08 15:02 ` Tobias Burnus
2022-07-07 10:34 ` [PATCH 03/17] libgomp, openmp: Add ompx_pinned_mem_alloc Andrew Stubbs
2022-07-07 10:34 ` [PATCH 04/17] openmp, nvptx: low-lat memory access traits Andrew Stubbs
2022-07-07 10:34 ` [PATCH 05/17] openmp, nvptx: ompx_unified_shared_mem_alloc Andrew Stubbs
2022-07-07 10:34 ` [PATCH 06/17] openmp: Add -foffload-memory Andrew Stubbs
2022-07-07 10:34 ` [PATCH 07/17] openmp: allow requires unified_shared_memory Andrew Stubbs
2022-07-07 10:34 ` [PATCH 08/17] openmp: -foffload-memory=pinned Andrew Stubbs
2022-07-07 11:54 ` Tobias Burnus [this message]
2022-07-07 22:18 ` Andrew Stubbs
2022-07-08 9:00 ` Tobias Burnus
2022-07-08 9:55 ` Andrew Stubbs
2022-07-08 9:57 ` Tobias Burnus
2023-02-20 14:59 ` Prototype 'GOMP_enable_pinned_mode' (was: [PATCH 08/17] openmp: -foffload-memory=pinned) Thomas Schwinge
2022-07-07 10:34 ` [PATCH 09/17] openmp: Use libgomp memory allocation functions with unified shared memory Andrew Stubbs
2022-07-07 10:34 ` [PATCH 10/17] Add parsing support for allocate directive (OpenMP 5.0) Andrew Stubbs
2022-07-07 10:34 ` [PATCH 11/17] Translate " Andrew Stubbs
2022-07-07 10:34 ` [PATCH 12/17] Handle cleanup of omp allocated variables " Andrew Stubbs
2022-07-07 10:34 ` [PATCH 13/17] Gimplify allocate directive " Andrew Stubbs
2022-07-07 10:34 ` [PATCH 14/17] Lower " Andrew Stubbs
2022-07-07 10:34 ` [PATCH 15/17] amdgcn: Support XNACK mode Andrew Stubbs
2022-07-07 10:34 ` [PATCH 16/17] amdgcn, openmp: Auto-detect USM mode and set HSA_XNACK Andrew Stubbs
2022-07-07 10:34 ` [PATCH 17/17] amdgcn: libgomp plugin USM implementation Andrew Stubbs
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