----- On Jun 14, 2018, at 10:00 AM, Florian Weimer fwei...@redhat.com wrote:
> On 06/14/2018 03:49 PM, Pavel Machek wrote: >> Hi! >> >>>>> - rseq_preempt(): on preemption, the scheduler sets the TIF_NOTIFY_RESUME >>>>> thread >>>>> flag, so rseq_handle_notify_resume() can check whether it's in a rseq >>>>> critical >>>>> section when returning to user-space, >>>>> - rseq_signal_deliver(): on signal delivery, rseq_handle_notify_resume() >>>>> checks >>>>> whether it's in a rseq critical section, >>>>> - rseq_migrate: on migration, the scheduler sets TIF_NOTIFY_RESUME as >>>>> well, >>>> >>>> Yes, this is not likely to be noticeable. >>>> >>>> But the proposal wanted to add a syscall to thread creation, right? >>>> And I believe that may be noticeable. >>> >>> Fair point! Do we have a standard benchmark that would stress this ? >> >> Web server performance benchmarks basically test clone() performance >> in many cases. > > Isn't that fork? I expect that the rseq arena is inherited on fork and > fork-type clone, otherwise it's going to be painful. On fork or clone creating a new process, the rseq tls area is inherited from the thread that does the fork syscall. On creation of a new thread with clone, there is no such inheritance. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
