Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-22 Thread Josh Triplett
On Sun, Feb 22, 2015 at 10:31:26AM -0800, Arjan van de Ven wrote: > >>To show the boot time, I'm using the timestamp of the "Write protecting" > >>line, > >>that's pretty much the last thing we print prior to ring 3 execution. > > > >That's a little sad; we ought to be write-protecting kernel

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-22 Thread Arjan van de Ven
To show the boot time, I'm using the timestamp of the "Write protecting" line, that's pretty much the last thing we print prior to ring 3 execution. That's a little sad; we ought to be write-protecting kernel read-only data as *early* as possible. well... if you are compromised before the

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-22 Thread Arjan van de Ven
To show the boot time, I'm using the timestamp of the Write protecting line, that's pretty much the last thing we print prior to ring 3 execution. That's a little sad; we ought to be write-protecting kernel read-only data as *early* as possible. well... if you are compromised before the

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-22 Thread Josh Triplett
On Sun, Feb 22, 2015 at 10:31:26AM -0800, Arjan van de Ven wrote: To show the boot time, I'm using the timestamp of the Write protecting line, that's pretty much the last thing we print prior to ring 3 execution. That's a little sad; we ought to be write-protecting kernel read-only data as

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 07:58:07PM -0800, Josh Triplett wrote: > On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: > > >> > > >>there's a few others as well that I'm chasing down... > > >>.. but the flip side, prior to running ring 3 code, why NOT do fast > > >>expedites? > > > >

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Josh Triplett
On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: > >> > >>there's a few others as well that I'm chasing down... > >>.. but the flip side, prior to running ring 3 code, why NOT do fast > >>expedites? > > > >It would be good to have before-and-after measurements of actual > >boot

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 05:08:52PM +0100, Peter Zijlstra wrote: > On Fri, Feb 20, 2015 at 09:45:39AM -0800, Arjan van de Ven wrote: > > On 2/20/2015 9:43 AM, Peter Zijlstra wrote: > > >On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > > >>there's a few others as well that I'm

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
y prani" > > > > Sent: Saturday, February 21, 2015 1:04:28 AM > > Subject: Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace > > periods > > > > On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: > > > On Fri, Fe

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: > >> > >>there's a few others as well that I'm chasing down... > >>.. but the flip side, prior to running ring 3 code, why NOT do fast > >>expedites? > > > >It would be good to have before-and-after measurements of actual > >boot

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 05:11:30PM +0100, Peter Zijlstra wrote: > On Fri, Feb 20, 2015 at 10:38:49AM -0800, Paul E. McKenney wrote: > > On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: > > > On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > > > > there's a few

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 10:38:49AM -0800, Paul E. McKenney wrote: > On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: > > On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > > > there's a few others as well that I'm chasing down... > > > .. but the flip side, prior to

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 09:45:39AM -0800, Arjan van de Ven wrote: > On 2/20/2015 9:43 AM, Peter Zijlstra wrote: > >On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > >>there's a few others as well that I'm chasing down... > >>.. but the flip side, prior to running ring 3 code, why

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Arjan van de Ven
there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? It would be good to have before-and-after measurements of actual boot time. Are these numbers available? To show the boot time, I'm using the timestamp of

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Mathieu Desnoyers
esnoyers" > , t...@linutronix.de, rost...@goodmis.org, > dhowe...@redhat.com, eduma...@google.com, > dvh...@linux.intel.com, fweis...@gmail.com, o...@redhat.com, "bobby prani" > > Sent: Saturday, February 21, 2015 1:04:28 AM > Subject: Re: [PATCH tip/core/rcu 0/4] Pr

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 07:58:07PM -0800, Josh Triplett wrote: On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? It would be good to

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Josh Triplett
On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? It would be good to have before-and-after measurements of actual boot time. Are these

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 05:08:52PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:45:39AM -0800, Arjan van de Ven wrote: On 2/20/2015 9:43 AM, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
Sent: Saturday, February 21, 2015 1:04:28 AM Subject: Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Arjan van de Ven
there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? It would be good to have before-and-after measurements of actual boot time. Are these numbers available? To show the boot time, I'm using the timestamp of

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 10:38:49AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Mathieu Desnoyers
/rcu 0/4] Programmatic nestable expedited grace periods On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: Does it really make a machine boot much

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 09:45:39AM -0800, Arjan van de Ven wrote: On 2/20/2015 9:43 AM, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 07:51:34AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? It would be good to have before-and-after measurements of actual boot time. Are these

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-21 Thread Paul E. McKenney
On Sat, Feb 21, 2015 at 05:11:30PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 10:38:49AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Josh Triplett
On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: > On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: > > On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: > > > Does it really make a machine boot much faster? Why are people using > > > synchronous gp

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 10:29:34AM -0800, Arjan van de Ven wrote: > On 2/20/2015 10:27 AM, Paul E. McKenney wrote: > >On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > >>Does it really make a machine boot much faster? Why are people using > >>synchronous gp primitives if

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: > On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > > there's a few others as well that I'm chasing down... > > .. but the flip side, prior to running ring 3 code, why NOT do fast > > expedites? > > So my

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
On 2/20/2015 10:27 AM, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about speed? Should we not fix that instead? The report I heard was that

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > Does it really make a machine boot much faster? Why are people using > synchronous gp primitives if they care about speed? Should we not fix > that instead? > >>> > >>>The report I heard was that it provided 10-15%

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
On 2/20/2015 9:43 AM, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? So my objections are twofold: - I object to

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: > there's a few others as well that I'm chasing down... > .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? So my objections are twofold: - I object to fast expedites in principle; they spray IPIs

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about speed? Should we not fix that instead? The report I heard was that it provided 10-15% faster boot times. That's not insignificant; got more details? I think we should really look

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: > On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: > > On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: > > > So I though we wanted to get rid / limit the expedited stuff because its > > > IPI happy,

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: > On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: > > So I though we wanted to get rid / limit the expedited stuff because its > > IPI happy, and here its spreading. > > Well, at least it no longer IPIs idle CPUs.

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: > On Thu, Feb 19, 2015 at 09:08:50PM -0800, Paul E. McKenney wrote: > > Hello! > > > > This series, possibly for v3.21, contains changes that allow in-kernel > > code to specify that all subsequent synchronous grace-period primitives

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Thu, Feb 19, 2015 at 09:08:50PM -0800, Paul E. McKenney wrote: > Hello! > > This series, possibly for v3.21, contains changes that allow in-kernel > code to specify that all subsequent synchronous grace-period primitives > (synchronize_rcu() and friends) be expedited. New rcu_expedite_gp() >

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Thu, Feb 19, 2015 at 09:08:50PM -0800, Paul E. McKenney wrote: Hello! This series, possibly for v3.21, contains changes that allow in-kernel code to specify that all subsequent synchronous grace-period primitives (synchronize_rcu() and friends) be expedited. New rcu_expedite_gp() and

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Josh Triplett
On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: Does it really make a machine boot much faster? Why are people using synchronous gp primitives

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 05:54:09PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: So I though we wanted to get rid / limit the expedited stuff because its IPI happy, and here

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? So my objections are twofold: - I object to fast expedites in principle; they spray IPIs

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: On Thu, Feb 19, 2015 at 09:08:50PM -0800, Paul E. McKenney wrote: Hello! This series, possibly for v3.21, contains changes that allow in-kernel code to specify that all subsequent synchronous grace-period primitives

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Peter Zijlstra
On Fri, Feb 20, 2015 at 08:37:37AM -0800, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 10:11:07AM +0100, Peter Zijlstra wrote: So I though we wanted to get rid / limit the expedited stuff because its IPI happy, and here its spreading. Well, at least it no longer IPIs idle CPUs. ;-)

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about speed? Should we not fix that instead? The report I heard was that it provided 10-15% faster boot times. That's not insignificant; got more details? I think we should really look

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
On 2/20/2015 9:43 AM, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? So my objections are twofold: - I object to

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about speed? Should we not fix that instead? The report I heard was that it provided 10-15% faster boot times.

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Arjan van de Ven
On 2/20/2015 10:27 AM, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about speed? Should we not fix that instead? The report I heard was that

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 10:29:34AM -0800, Arjan van de Ven wrote: On 2/20/2015 10:27 AM, Paul E. McKenney wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: Does it really make a machine boot much faster? Why are people using synchronous gp primitives if they care about

Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-20 Thread Paul E. McKenney
On Fri, Feb 20, 2015 at 06:43:59PM +0100, Peter Zijlstra wrote: On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote: there's a few others as well that I'm chasing down... .. but the flip side, prior to running ring 3 code, why NOT do fast expedites? So my objections are

[PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-19 Thread Paul E. McKenney
Hello! This series, possibly for v3.21, contains changes that allow in-kernel code to specify that all subsequent synchronous grace-period primitives (synchronize_rcu() and friends) be expedited. New rcu_expedite_gp() and rcu_unexpedite_gp() primitives enable and disable expediting, and these

[PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods

2015-02-19 Thread Paul E. McKenney
Hello! This series, possibly for v3.21, contains changes that allow in-kernel code to specify that all subsequent synchronous grace-period primitives (synchronize_rcu() and friends) be expedited. New rcu_expedite_gp() and rcu_unexpedite_gp() primitives enable and disable expediting, and these