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Re: TSX lock elision for glibc v15


On 06/28/2013 04:53 PM, Andi Kleen wrote:
> Proposed NEWS entry:
> 
> * Added support for TSX lock elision for pthread mutexes and read/write
>   locks on i386 and x86-64.
>   This allows to improve lock scaling of existing programs.
>   When the --enable-lock-elision=yes parameter is specified at configure
>   time lock elision will be enabled by default for all PTHREAD_MUTEX_DEFAULT
>   mutexes and rwlock.
> 
> History:
> + v15: 
>     Readd hunk lost in v14 to set rwlock status
>     Remove most extra test cases for extra lock types.
>     Split test suite in minimal fixes and pure elision test cases.
>     Elision test cases are only done late in the series now.
>     Remove environment variable checks in test suite.
>     Move manual in series. Typo fixes for manual (thanks Carlos)
>     Rename --enable-lock-elision=on to yes
>     Split configure changes.
>     Fix some broken ChangeLogs.

At present I feel that patches 1 - 7 could be committed immediately
as a no-ABI/no-API checkpoint for elision which would allow you to
build and test with elision turned on via configuring with
--enable-elision=yes.

The only thing that blocks this is a need for consensus on patch
#6 to add elision to rwlocks. I would like someone else to agree
with Andi and my interpretation that deadlock on relock is not
required by POSIX for rwlocks.

Patches 8 through 14 are under review.

Cheers,
Carlos.




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