Re: [lttng-dev] Alternative to signals/sys_membarrier() in liburcu

2015-03-23 Thread Duncan Sands
So, given the fact that the userspace RCU library does now see some real-world use, is it now time for Mathieu to resubmit his sys_membarrier() patch? I'm using userspace RCU with success in financial software, so the LTTng project isn't the only user. It works well, but it's not as fast as I'

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-14 Thread Benjamin Herrenschmidt
On Thu, 2015-03-12 at 14:12 -0700, Paul E. McKenney wrote: > > Are there any architectures left that use hardware-assisted global > TLB invalidation? ARM and PowerPC at least... Cheers, Ben. > On such an architecture, you might not get a memory > barrier except on the CPU executing the mprote

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-13 Thread Paul E. McKenney
g-...@lists.lttng.org, > > > "LKML" , "Paul E. > > > McKenney" , "Peter Zijlstra" > > > , "Ingo Molnar" , > > > "Thomas Gleixner" , "Steven Rostedt" > > > > > > Se

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-13 Thread Ingo Molnar
; , "Peter Zijlstra" > > , "Ingo Molnar" , > > "Thomas Gleixner" , "Steven Rostedt" > > > > Sent: Thursday, March 12, 2015 5:47:05 PM > > Subject: Re: Alternative to signals/sys_membarrier() in liburcu > > > > On

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread Mathieu Desnoyers
r" > , "Paul E. McKenney" , "Linus > Torvalds" > , "Ingo Molnar" > Sent: Thursday, March 12, 2015 7:59:38 PM > Subject: Re: Alternative to signals/sys_membarrier() in liburcu > > On Thu, 12 Mar 2015 20:56:00 + (UTC) > Mathieu Desnoyers

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread One Thousand Gnomes
On Thu, 12 Mar 2015 20:56:00 + (UTC) Mathieu Desnoyers wrote: > (sorry for re-send, my mail client tricked me into posting HTML > to lkml) > > Hi, > > Michael Sullivan proposed a clever hack abusing mprotect() to > perform the same effect as sys_membarrier() I submitted a few > years ago

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread Mathieu Desnoyers
t; , > "Thomas Gleixner" , "Steven Rostedt" > Sent: Thursday, March 12, 2015 5:47:05 PM > Subject: Re: Alternative to signals/sys_membarrier() in liburcu > > On Thu, Mar 12, 2015 at 1:53 PM, Mathieu Desnoyers > wrote: > > > > So the question as it stan

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread Linus Torvalds
On Thu, Mar 12, 2015 at 1:53 PM, Mathieu Desnoyers wrote: > > So the question as it stands appears to be: would you be comfortable > having users abuse mprotect(), relying on its side-effect of issuing > a smp_mb() on each targeted CPU for the TLB shootdown, as > an effective implementation of pro

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread Paul E. McKenney
gt; Thanks! > > Mathieu > > > > > > From: "Michael Sullivan" > To: "Mathieu Desnoyers" > Cc: lttng-...@lists.lttng.org > Sent: Thursday, March 12, 2015 12:04:07 PM > Subject: Re: [lttng-dev] Alternative to signals/sys_membarrier() in

Re: Alternative to signals/sys_membarrier() in liburcu

2015-03-12 Thread Mathieu Desnoyers
implementation of process-wide memory barrier ? Thoughts ? Thanks! Mathieu From: "Michael Sullivan" To: "Mathieu Desnoyers" Cc: lttng-...@lists.lttng.org Sent: Thursday, March 12, 2015 12:04:07 PM Subject: Re: [lttng-dev] Alternative to signals/sys_membarrier()