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Task #1382

drop old CUDA support (3.2 and/or 4.0)

Added by Szilárd Páll over 3 years ago. Updated over 3 years ago.

Status:
Closed
Priority:
Low
Category:
mdrun
Target version:
Difficulty:
uncategorized
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Description

Dropping support for older CUDA version would not only allow code simplification, but also less testing. The versions in question are v3.2 (released Nov 2010) and v4.0 (May 2011).

Dropping v3.2 support would allow switching to page-locking memory using cudaHostRegister() instead of having to call cudaHotsMalloc() for the CPU-side memory that will be used in transfers to/from the GPU. Note that alignment and size requirements (page size dependent) apply.

Also dropping v4.0 support would allow removing the "legacy" kernels which are only used with the <=v4.1 CUDA versions.

While the former would make it impossible to build with CUDA 3.2, the drawback of the latter is only performance degradation. Also note that much of the Fermi hardware was launched in the 3.2-4.0 era and many are sticking to the old/original drivers like v270.x (older kernel dependency, stubbornness?) which means that they are limited to these older CUDA versions as newer CUDA requires newer drivers.


Related issues

Related to GROMACS - Task #1456: remove the use of nbat->alloc/free pointers New 03/06/2014

Associated revisions

Revision 2c0c359c (diff)
Added by Szilárd Páll over 3 years ago

remove legacy CUDA non-bonded kernels

This commit drops the legacy set of kernels which were optimized for use
with CUDA compilers 3.2 and 4.0 (previous to the switch to llvm backend
in 4.1).

For now the only consequence is slight performance degradation with CUDA
3.2/4.0, the build system still requires CUDA >=3.2 as the kernels do
build with the older CUDA compilers. Whether to require at least CUDA
4.1 will be decided later.

Refs #1382

Change-Id: I75d31b449e5b5e10f823408e23f35b9a7ac68bae

Revision 1bcf0ded (diff)
Added by Szilárd Páll over 3 years ago

Bump required CUDA version to 4.0

- Added warning with CUDA 4.0;
- Fixed some typos in comments;
- Fixed the comment referring to GPU code generation with CUDA v5.0+.

Fixes #1382

Change-Id: Iee182ace765022fc6a179531d42e965594cff104

History

#1 Updated by Mark Abraham over 3 years ago

Sounds good - resources are limited and we need to focus on the things that deliver value to us (i.e. performance on recent compute stacks).

#2 Updated by Szilárd Páll over 3 years ago

+ we'll need a few more sets of kernels for shift/switch and hopefully energy groups for which we'd have to maintain a set of legacy kernels as well. Initially the work required to root out the legacy stuff may be rather high, but in the long term it will pay off.

After discussing with Berk, we decided that I'll drop a mail to gmx-users and gmx-dev to see whether there are any stuck with old CUDA.

However, note that I will prioritize features rather than this code maintenance - at least for 5.0.

#3 Updated by Szilárd Páll over 3 years ago

  • Status changed from New to In Progress

To complete this task we should require at least CUDA 4.0 or possibly 4.1.

#4 Updated by Szilárd Páll over 3 years ago

  • Target version changed from 5.x to 5.0

Bump the requirement to CUDA 4.0 and possibly remove the use of nbat->alloc/free pointers and instead use with CUDA the page-locking functionality in the CUDA RT API.

#5 Updated by Gerrit Code Review Bot over 3 years ago

Gerrit received a related patchset '1' for Issue #1382.
Uploader: Szilárd Páll ()
Change-Id: Iee182ace765022fc6a179531d42e965594cff104
Gerrit URL: https://gerrit.gromacs.org/3203

#6 Updated by Szilárd Páll over 3 years ago

  • Related to Task #1456: remove the use of nbat->alloc/free pointers added

#7 Updated by Szilárd Páll over 3 years ago

  • Status changed from In Progress to Resolved
  • % Done changed from 0 to 100

#8 Updated by Roland Schulz over 3 years ago

  • Status changed from Resolved to Closed

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