Prototype 'GOMP_enable_pinned_mode' (was: [PATCH 08/17] openmp: -foffload-memory=pinned)
Commit Message
Hi!
On 2022-07-07T23:18:03+0100, Andrew Stubbs <ams@codesourcery.com> wrote:
> On 07/07/2022 12:54, Tobias Burnus wrote:
>> 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?
I agree. (But I'm not working on that, for avoidance of doubt.)
>> (Okay, I have to admit that the final patch was only committed on
>> Monday. But still ...)
>
> Possibly, I had most of this done before then. I'll have a look next
> time I visit this patch.
Until then, let's at least document/verify 'GOMP_enable_pinned_mode';
I've pushed to devel/omp/gcc-12
commit 9657d906869e098340c23118c2eb8592d9e77ac5
"Prototype 'GOMP_enable_pinned_mode'", see attached.
Grüße
Thomas
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From 9657d906869e098340c23118c2eb8592d9e77ac5 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Mon, 20 Feb 2023 15:29:44 +0100
Subject: [PATCH] Prototype 'GOMP_enable_pinned_mode'
Fix-up for og12 commit 842df187487f5b16ae29bbe7e9acd79661a9df48
"openmp: -foffload-memory=pinned". No functional change.
libgomp/
* libgomp_g.h (GOMP_enable_pinned_mode): New.
---
libgomp/ChangeLog.omp | 2 ++
libgomp/libgomp_g.h | 1 +
2 files changed, 3 insertions(+)
@@ -1,5 +1,7 @@
2023-02-20 Thomas Schwinge <thomas@codesourcery.com>
+ * libgomp_g.h (GOMP_enable_pinned_mode): New.
+
* config/linux/allocator.c (linux_memspace_alloc): Add 'init0'
formal parameter. Adjust all users.
(linux_memspace_alloc, linux_memspace_free): Attempt to allocate
@@ -375,6 +375,7 @@ extern void GOMP_teams_reg (void (*) (void *), void *, unsigned, unsigned,
extern void *GOMP_alloc (size_t, size_t, uintptr_t);
extern void GOMP_free (void *, uintptr_t);
+extern void GOMP_enable_pinned_mode (void);
/* error.c */
--
2.25.1