Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2015-01-13 Thread Luis R. Rodriguez
On Thu, Dec 18, 2014 at 02:23:14PM -0500, Konrad Rzeszutek Wilk wrote: > > index 000..b5a3e98 > > --- /dev/null > > +++ b/drivers/xen/preempt.c > > @@ -0,0 +1,17 @@ > > +/* > > + * Preemptible hypercalls > > + * > > + * Copyright (C) 2014 Citrix Systems R&D ltd. > > + * > > + * This source code

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-18 Thread Konrad Rzeszutek Wilk
> index 000..b5a3e98 > --- /dev/null > +++ b/drivers/xen/preempt.c > @@ -0,0 +1,17 @@ > +/* > + * Preemptible hypercalls > + * > + * Copyright (C) 2014 Citrix Systems R&D ltd. > + * > + * This source code is free software; you can redistribute it and/or > + * modify it under the terms of the GN

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-11 Thread Luis R. Rodriguez
On Thu, Dec 11, 2014 at 11:09:42AM +, David Vrabel wrote: > On 10/12/14 23:51, Andy Lutomirski wrote: > > On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez > > All that being said, this is IMO a bit gross. You've added a bunch of > > asm that's kind of like a parallel error_exit, and the erro

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-11 Thread Luis R. Rodriguez
On Thu, Dec 11, 2014 at 10:47:44AM -0800, H. Peter Anvin wrote: > On 12/10/2014 05:03 PM, Luis R. Rodriguez wrote: > > > > This is an issue onloy for for non*-preemptive kernels. > > > > Some of Xen's hypercalls can take a long time and unfortunately for > > *non*-preemptive kernels this can be q

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-11 Thread H. Peter Anvin
On 12/10/2014 05:03 PM, Luis R. Rodriguez wrote: > > This is an issue onloy for for non*-preemptive kernels. > > Some of Xen's hypercalls can take a long time and unfortunately for > *non*-preemptive kernels this can be quite a bit of an issue. > We've handled situations like this with cond_resch

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-11 Thread David Vrabel
On 10/12/14 23:51, Andy Lutomirski wrote: > On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez >> --- a/arch/x86/kernel/entry_64.S >> +++ b/arch/x86/kernel/entry_64.S >> @@ -1170,7 +1170,23 @@ ENTRY(xen_do_hypervisor_callback) # >> do_hypervisor_callback(struct *pt_regs) >> popq %rsp >>

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread Andy Lutomirski
On Wed, Dec 10, 2014 at 4:55 PM, Luis R. Rodriguez wrote: > On Wed, Dec 10, 2014 at 03:51:48PM -0800, Andy Lutomirski wrote: >> On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez >> wrote: >> > From: "Luis R. Rodriguez" >> > >> > Xen has support for splitting heavy work work into a series >> > o

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread Luis R. Rodriguez
On Wed, Dec 10, 2014 at 04:29:06PM -0800, H. Peter Anvin wrote: > On 12/10/2014 03:34 PM, Luis R. Rodriguez wrote: > > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S > > index 344b63f..40b5c0c 100644 > > --- a/arch/x86/kernel/entry_32.S > > +++ b/arch/x86/kernel/entry_32.S > >

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread Luis R. Rodriguez
On Wed, Dec 10, 2014 at 03:51:48PM -0800, Andy Lutomirski wrote: > On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez > wrote: > > From: "Luis R. Rodriguez" > > > > Xen has support for splitting heavy work work into a series > > of hypercalls, called multicalls, and preempting them through > > wh

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread H. Peter Anvin
On 12/10/2014 03:34 PM, Luis R. Rodriguez wrote: > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S > index 344b63f..40b5c0c 100644 > --- a/arch/x86/kernel/entry_32.S > +++ b/arch/x86/kernel/entry_32.S > @@ -982,7 +982,28 @@ ENTRY(xen_hypervisor_callback) > ENTRY(xen_do_upcall)

Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread Andy Lutomirski
On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez wrote: > From: "Luis R. Rodriguez" > > Xen has support for splitting heavy work work into a series > of hypercalls, called multicalls, and preempting them through > what Xen calls continuation [0]. Despite this though without > CONFIG_PREEMPT pre

[Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

2014-12-10 Thread Luis R. Rodriguez
From: "Luis R. Rodriguez" Xen has support for splitting heavy work work into a series of hypercalls, called multicalls, and preempting them through what Xen calls continuation [0]. Despite this though without CONFIG_PREEMPT preemption won't happen and while enabling CONFIG_RT_GROUP_SCHED can at t