Re: [dpdk-dev] add support for HTM lock elision for x86

[Roman Dementiev <roman.dementiev@intel.com>]

Hello Jay,

Tuesday, June 2, 2015, 3:21:24 PM, you wrote:

> On Tue, Jun 2, 2015 at 8:11 AM, Roman Dementiev <roman.dementiev@intel.com>wrote:


>  This series of patches adds methods that use hardware memory transactions (HTM)
>  on fast-path for DPDK locks (a.k.a. lock elision). Here the methods are implemented
>  for x86 using Restricted Transactional Memory instructions (Intel(r) Transactional
>  Synchronization Extensions). The implementation fall-backs to the normal DPDK lock
>  if HTM is not available or memory transactions fail.


It provides a very good scaling given the protected data structure is friendly
to HTM. One example is rte_hash which is benchmarked in the unit test I have 
provided as the last patch.

There are some papers showing additional test results with similar lock 
elision implementations: www.intel.com/software/tsx


> This is very interesting. Do you have any summary you can give us
> of what the performance implications are from your test data?
>  
>  This is not a replacement for lock usages since not all critical sections protected
>  by locks are friendly to HTM.



> Any pointers to material that describe where HTM in its current incarnation on x86 is approprate?
>  
>


I meant to say: not a replacement to *ALL* lock usages. You can check the material here: www.intel.com/software/tsx
Please let me know if you need additional information.


>  Roman Dementiev (3):
>   spinlock: add support for HTM lock elision for x86
>   rwlock: add support for HTM lock elision for x86
>   test scaling of HTM lock elision protecting rte_hash
>  
>   app/test/Makefile                                  |   1 +
>   app/test/test_hash_scaling.c                       | 223 +++++++++++++++++++++
>   lib/librte_eal/common/Makefile                     |   4 +-
>   .../common/include/arch/ppc_64/rte_rwlock.h        |  38 ++++
>   .../common/include/arch/ppc_64/rte_spinlock.h      |  41 ++++
>   lib/librte_eal/common/include/arch/x86/rte_rtm.h   |  73 +++++++
>   .../common/include/arch/x86/rte_rwlock.h           |  82 ++++++++
>   .../common/include/arch/x86/rte_spinlock.h         | 107 ++++++++++
>   lib/librte_eal/common/include/generic/rte_rwlock.h | 194 ++++++++++++++++++
>   .../common/include/generic/rte_spinlock.h          |  75 +++++++
>   lib/librte_eal/common/include/rte_rwlock.h         | 158 ---------------
>   11 files changed, 836 insertions(+), 160 deletions(-)




> Thanks!
> Jay 



-- 
Best regards,
 Roman                            mailto:roman.dementiev@intel.com

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