Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-02-01 Thread Paul E. McKenney
On Thu, Jan 31, 2019 at 10:47:50AM -0800, Alexei Starovoitov wrote: > On Thu, Jan 31, 2019 at 06:01:56AM -0800, Paul E. McKenney wrote: > > On Wed, Jan 30, 2019 at 02:57:43PM -0800, Alexei Starovoitov wrote: > > > On Wed, Jan 30, 2019 at 01:05:36PM -0800, Paul E. McKenney wrote: > > > > On Wed, Jan

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-31 Thread Alexei Starovoitov
On Thu, Jan 31, 2019 at 06:01:56AM -0800, Paul E. McKenney wrote: > On Wed, Jan 30, 2019 at 02:57:43PM -0800, Alexei Starovoitov wrote: > > On Wed, Jan 30, 2019 at 01:05:36PM -0800, Paul E. McKenney wrote: > > > On Wed, Jan 30, 2019 at 11:51:14AM -0800, Alexei Starovoitov wrote: > > > > On Wed, Jan

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-31 Thread Paul E. McKenney
On Wed, Jan 30, 2019 at 02:57:43PM -0800, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 01:05:36PM -0800, Paul E. McKenney wrote: > > On Wed, Jan 30, 2019 at 11:51:14AM -0800, Alexei Starovoitov wrote: > > > On Wed, Jan 30, 2019 at 10:36:18AM -0800, Paul E. McKenney wrote: > > > > On Wed, Jan

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 01:05:36PM -0800, Paul E. McKenney wrote: > On Wed, Jan 30, 2019 at 11:51:14AM -0800, Alexei Starovoitov wrote: > > On Wed, Jan 30, 2019 at 10:36:18AM -0800, Paul E. McKenney wrote: > > > On Wed, Jan 30, 2019 at 06:11:00PM +, Will Deacon wrote: > > > > Hi Alexei, > > > >

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Paul E. McKenney
On Wed, Jan 30, 2019 at 11:51:14AM -0800, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 10:36:18AM -0800, Paul E. McKenney wrote: > > On Wed, Jan 30, 2019 at 06:11:00PM +, Will Deacon wrote: > > > Hi Alexei, > > > > > > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote:

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 10:36:18AM -0800, Paul E. McKenney wrote: > On Wed, Jan 30, 2019 at 06:11:00PM +, Will Deacon wrote: > > Hi Alexei, > > > > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > > > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > > >

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 06:11:00PM +, Will Deacon wrote: > Assuming that a desirable property of an eBPF program is portability between > CPU architectures, then you're effectively forcing the programmer to "assume that is fundamental misunderstanding that being thrown in this thread. bpf is n

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 09:58:50AM +0100, Peter Zijlstra wrote: > On Tue, Jan 29, 2019 at 06:32:13PM -0800, Alexei Starovoitov wrote: > > On Tue, Jan 29, 2019 at 10:16:54AM +0100, Peter Zijlstra wrote: > > > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > > > > On Mon, Jan 28,

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Paul E. McKenney
On Wed, Jan 30, 2019 at 06:11:00PM +, Will Deacon wrote: > Hi Alexei, > > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > > On Fri, Jan 25, 2019 at 04:17:26PM -0800, Alexei Starovoitov wrote: > > > > Wh

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Will Deacon
Hi Alexei, On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > On Fri, Jan 25, 2019 at 04:17:26PM -0800, Alexei Starovoitov wrote: > > > What I want to avoid is to define the whole execution ordering model > > >

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-30 Thread Peter Zijlstra
On Tue, Jan 29, 2019 at 06:32:13PM -0800, Alexei Starovoitov wrote: > On Tue, Jan 29, 2019 at 10:16:54AM +0100, Peter Zijlstra wrote: > > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > > > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > > > > > Ah, but th

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-29 Thread Alexei Starovoitov
On Tue, Jan 29, 2019 at 10:16:54AM +0100, Peter Zijlstra wrote: > On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > > > Ah, but the loop won't be in the BPF program itself. The BPF program > > > would only ha

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-29 Thread Peter Zijlstra
On Mon, Jan 28, 2019 at 01:56:24PM -0800, Alexei Starovoitov wrote: > On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > > Ah, but the loop won't be in the BPF program itself. The BPF program > > would only have had the BPF_SPIN_LOCK instruction, the JIT them emits > > code similar

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-28 Thread Alexei Starovoitov
On Mon, Jan 28, 2019 at 10:24:08AM +0100, Peter Zijlstra wrote: > On Fri, Jan 25, 2019 at 04:17:26PM -0800, Alexei Starovoitov wrote: > > On Fri, Jan 25, 2019 at 11:23:12AM +0100, Peter Zijlstra wrote: > > > On Thu, Jan 24, 2019 at 03:58:59PM -0800, Alexei Starovoitov wrote: > > > > On Thu, Jan 24,

Re: bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-28 Thread Peter Zijlstra
On Fri, Jan 25, 2019 at 04:17:26PM -0800, Alexei Starovoitov wrote: > On Fri, Jan 25, 2019 at 11:23:12AM +0100, Peter Zijlstra wrote: > > On Thu, Jan 24, 2019 at 03:58:59PM -0800, Alexei Starovoitov wrote: > > > On Thu, Jan 24, 2019 at 07:01:09PM +0100, Peter Zijlstra wrote: > > > > > > And this w

bpf memory model. Was: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock

2019-01-25 Thread Alexei Starovoitov
On Fri, Jan 25, 2019 at 11:23:12AM +0100, Peter Zijlstra wrote: > On Thu, Jan 24, 2019 at 03:58:59PM -0800, Alexei Starovoitov wrote: > > On Thu, Jan 24, 2019 at 07:01:09PM +0100, Peter Zijlstra wrote: > > > > And this would again be the moment where I go pester you about the BPF > > > memory mode