From: Tom de Vries <tdevries@suse.de>
To: Andrew Stubbs <ams@codesourcery.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: Tobias Burnus <tobias@codesourcery.com>,
Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH] libgomp, OpenMP, nvptx: Low-latency memory allocator
Date: Thu, 6 Jan 2022 10:29:29 +0100 [thread overview]
Message-ID: <5e75a64c-a8d3-2d2a-162a-a3ea79358b48@suse.de> (raw)
In-Reply-To: <bfe2c7c8-6374-91ea-2587-805c57497b14@codesourcery.com>
On 1/5/22 15:36, Andrew Stubbs wrote:
> On 05/01/2022 13:04, Tom de Vries wrote:
>> On 1/5/22 12:08, Tom de Vries wrote:
>>> The allocators-1.c test-case doesn't compile because:
>>> ...
>>> FAIL: libgomp.c/allocators-1.c (test for excess errors)
>>> Excess errors:
>>> /home/vries/oacc/trunk/source-gcc/libgomp/testsuite/libgomp.c/allocators-1.c:7:22:
>>> sorry, unimplemented: ' ' clause on 'requires' directive not
>>> supported yet
>>>
>>> UNRESOLVED: libgomp.c/allocators-1.c compilation failed to produce
>>> executable
>>> ...
>>>
>>> So, I suppose I need "[PATCH] OpenMP front-end: allow requires
>>> dynamic_allocators" as well, I'll try again with that applied.
>>
>> After applying that, I get:
>> ...
>> WARNING: program timed out.
>> FAIL: libgomp.c/allocators-2.c execution test
>> WARNING: program timed out.
>> FAIL: libgomp.c/allocators-3.c execution test
>> ...
>
> It works for me.....
>
> Those tests are doing some large number of allocations repeatedly and in
> parallel to stress the atomics. They're also slightly longer running
> than the other tests.
> - allocators-2 calls omp_alloc 8080 times, over 16 kernel launches,
> some of which will fall back to PTX malloc.
I've minimized the test-case by enabling a single call in main at a
time. All but the last 4 take about two seconds, the last 4 hang (and
time out at 5min).
So, this already times out for me:
...
int
main ()
{
test (1000, omp_low_lat_mem_alloc);
return 0;
}
...
I tried playing around with the n, and roughly there's no hang below
100, and a hang above 200, and inbetween there may or may not be a hang.
Again the same dynamic: if there's no hang, it just takes a few seconds.
> - allocators-3 calls omp_alloc and omp_free 8 million times each,
> over 8 kernel launches, and takes about a minute to run on my device
> (whether that falls back depends entirely on how the free calls
> interleave).
>
> Either there is a flaw in the concurrency causing some kind of deadlock,
> or else your timeout is set too short for your device. I hope it's the
> latter. We may need to tweak this.
At first glance, the above behaviour doesn't look like a too short timeout.
[ FTR, I'm using a GT 1030 with production branch driver version 470.86
(which is one version behind the latest 470.94) ]
Thanks,
- Tom
next prev parent reply other threads:[~2022-01-06 9:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 15:58 Andrew Stubbs
2021-12-21 11:33 ` [PATCH] nvptx: bump default to PTX 4.1 Andrew Stubbs
2022-01-05 10:24 ` Tom de Vries
2022-01-05 10:33 ` Andrew Stubbs
2022-01-05 12:45 ` Tom de Vries
2022-01-05 11:08 ` [PATCH] libgomp, OpenMP, nvptx: Low-latency memory allocator Tom de Vries
2022-01-05 13:04 ` Tom de Vries
2022-01-05 14:36 ` Andrew Stubbs
2022-01-06 9:29 ` Tom de Vries [this message]
2022-01-06 17:53 ` Tom de Vries
2022-01-07 14:14 ` Andrew Stubbs
2022-01-13 11:13 ` Andrew Stubbs
2023-02-14 12:54 ` [og12] In 'libgomp/allocator.c:omp_realloc', route 'free' through 'MEMSPACE_FREE' (was: [PATCH] libgomp, OpenMP, nvptx: Low-latency memory allocator) Thomas Schwinge
2023-02-14 15:11 ` Andrew Stubbs
2023-02-16 21:45 ` Thomas Schwinge
2022-01-05 14:21 ` [PATCH] libgomp, OpenMP, nvptx: Low-latency memory allocator Andrew Stubbs
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