Torvald Riegel <trie...@redhat.com> writes: > On Thu, 2012-11-08 at 17:23 -0800, Richard Henderson wrote: >> + // Honor an abort from abortTransaction. >> + else if (htm_abort_is_cancel(ret)) >> + return a_abortTransaction | a_restoreLiveVariables; > > The problem is that we cannot reliably detect whether an abort with a > certain abort reason code really means that we got canceled. A nested > transaction is one example: how do we distinguish whether the nested or > the outermost transaction were canceled?.
In TSX you always come back to the outermost anyways. Look at the nested bit in the abort code? > Thus, there are two options for how to handle transactions that may > abort: Either execute them transactionally the first time, and do an > explicit HTM abort on transaction_cancel that tells libitm not not retry > as HW transaction, or execute such transactions always as SW > transactions. Which of these two options is better depends on how > frequently transaction_cancel would actually be called. If it's > infrequent, then trying to run as HW transactions might be better. I believe the current evidence is that cancel is very uncommon. -Andi -- a...@linux.intel.com -- Speaking for myself only
