Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-08-21 Thread Gleb Natapov
On Fri, Jul 29, 2016 at 11:22:18AM -0600, Jeff Law wrote: > On 07/29/2016 11:19 AM, Gleb Natapov wrote: > > > > I'll table your patch on that assumption. > > OK. Can you ping him about it after he will back or should I (although in > > another week I will be on PTO :))? We are suffering from unwin

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-29 Thread Gleb Natapov
On Fri, Jul 29, 2016 at 10:54:21AM -0600, Jeff Law wrote: > On 07/29/2016 10:03 AM, Jeff Law wrote: > > > > It's been a couple years since I've really thought about these kinds of > > > > synchronization issues -- is it really safe in a weakly ordered > > > > processor to > > > > rely on the mutex

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-29 Thread Jeff Law
On 07/29/2016 11:19 AM, Gleb Natapov wrote: I'll table your patch on that assumption. OK. Can you ping him about it after he will back or should I (although in another week I will be on PTO :))? We are suffering from unwind scalability problems in C++ exceptions and although this one patch will

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-29 Thread Gleb Natapov
On Fri, Jul 29, 2016 at 10:03:53AM -0600, Jeff Law wrote: > On 07/27/2016 10:24 PM, Gleb Natapov wrote: > > On Wed, Jul 27, 2016 at 05:12:18PM -0600, Jeff Law wrote: > > > On 07/25/2016 07:44 AM, Gleb Natapov wrote: > > > > _Unwind_Find_FDE calls _Unwind_Find_registered_FDE and it takes lock > > >

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-29 Thread Jeff Law
On 07/29/2016 10:03 AM, Jeff Law wrote: It's been a couple years since I've really thought about these kinds of synchronization issues -- is it really safe in a weakly ordered processor to rely on the mutex lock/unlock of the "object_mutex" to order the loads/stores of "unseen_objects" and "seen_

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-29 Thread Jeff Law
On 07/27/2016 10:24 PM, Gleb Natapov wrote: On Wed, Jul 27, 2016 at 05:12:18PM -0600, Jeff Law wrote: On 07/25/2016 07:44 AM, Gleb Natapov wrote: _Unwind_Find_FDE calls _Unwind_Find_registered_FDE and it takes lock even when there is no registered objects. As far as I see only statically linked

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-27 Thread Gleb Natapov
On Wed, Jul 27, 2016 at 05:12:18PM -0600, Jeff Law wrote: > On 07/25/2016 07:44 AM, Gleb Natapov wrote: > > _Unwind_Find_FDE calls _Unwind_Find_registered_FDE and it takes lock even > > when there is no registered objects. As far as I see only statically > > linked applications call __register_fram

Re: [PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-27 Thread Jeff Law
On 07/25/2016 07:44 AM, Gleb Natapov wrote: _Unwind_Find_FDE calls _Unwind_Find_registered_FDE and it takes lock even when there is no registered objects. As far as I see only statically linked applications call __register_frame_info* functions, so for dynamically linked executables taking the lo

[PATCH] do not take mutex in _Unwind_Find_registered_FDE if there is no registered objects

2016-07-25 Thread Gleb Natapov
_Unwind_Find_FDE calls _Unwind_Find_registered_FDE and it takes lock even when there is no registered objects. As far as I see only statically linked applications call __register_frame_info* functions, so for dynamically linked executables taking the lock to check unseen_objects and seen_objects is