From: David Vrabel <david.vrabel@citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>, xen-devel@lists.xen.org
Subject: Re: [PATCH 12/12] xen/events: use the FIFO-based ABI if available
Date: Mon, 19 Aug 2013 12:55:08 +0100 [thread overview]
Message-ID: <5212079C.8040304@citrix.com> (raw)
In-Reply-To: <20130816174723.GJ12674@zion.uk.xensource.com>
On 16/08/13 18:47, Wei Liu wrote:
> On Fri, Aug 09, 2013 at 07:15:21PM +0100, David Vrabel wrote:
>> From: David Vrabel <david.vrabel@citrix.com>
>>
>> If the hypervisor supports the FIFO-based ABI, enable it by
>> initializing the control block for the boot VCPU and subsequent VCPUs
>> as they are brought up. The event array is expanded as required when
>> event ports are setup.
>>
>> This implementation has some known limitations:
... because I haven't implemented them yet.
>> - Migration will not work as the control blocks or event arrays are
>> not remapped by Xen at the destination.
>>
>
> Is it possible to hook into xen_vcpu_restore to make it work?
Yes, I think so.
>> - The timer VIRQ which previously was treated as the highest priority
>> event has the default priority.
>>
>
> So what's missing from the series is a patch that allows kernel to
> actually make use of the priority queues? IMHO it's not just about the
> timer VIRQ. How do you plan to expose this interface to drivers?
There will be Xen-specific xen_evtchn_set_priority() call. I don't
think it can be usefully exposed to non-Xen-specific hardware drivers
using PIRQs.
I expect to use this for boosting the priority of the timer interrupt only.
>> +static int __cpuinit fifo_cpu_notification(struct notifier_block *self,
>> + unsigned long action, void *hcpu)
>> +{
>> + int cpu = (long)hcpu;
>> + int ret = 0;
>> +
>> + switch (action) {
>> + case CPU_UP_PREPARE:
>> + ret = fifo_init_control_block(cpu);
>> + break;
>
> On the hypervisor side fifo_init_control_block would return -EINVAL if
> this CPU has previous mapped control block.
I need to look into this -- CPU hotplug is not something I really looked
at or tried yet. Probably need to check if we have already done this.
> Do you need to tear down the control block when you offline a CPU? (That
> would mean another sub-op for the interface)
None of the other per-VCPU is state appears to be cleaned up when a
guest offlines a VCPU. e.g., there is a VCPUOP_register_vcpu_info but
no VCPUOP_unregister_vcpu_info.
David
next prev parent reply other threads:[~2013-08-19 11:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-09 18:15 [RFC PATCHv2 00/12] Linux: FIFO-based event channel ABI David Vrabel
2013-08-09 18:15 ` [PATCH 01/12] xen/events: refactor retrigger_dynirq() and resend_irq_on_evtchn() David Vrabel
2013-08-16 17:46 ` Wei Liu
2013-09-05 17:28 ` David Vrabel
2013-08-09 18:15 ` [PATCH 02/12] xen/events: remove unnecessary init_evtchn_cpu_bindings() David Vrabel
2013-08-09 18:15 ` [PATCH 03/12] xen/events: introduce test_and_set_mask David Vrabel
2013-08-09 18:15 ` [PATCH 04/12] xen/events: replace raw bit ops with functions David Vrabel
2013-08-09 18:15 ` [PATCH 05/12] xen/events: move drivers/xen/events.c into drivers/xen/events/ David Vrabel
2013-08-09 18:15 ` [PATCH 06/12] xen/events: move 2-level specific code into its own file David Vrabel
2013-08-09 18:15 ` [PATCH 07/12] xen/events: add struct evtchn_ops for the low-level port operations David Vrabel
2013-08-16 17:47 ` Wei Liu
2013-08-19 10:39 ` David Vrabel
2013-08-19 10:52 ` Wei Liu
2013-08-09 18:15 ` [PATCH 08/12] xen/events: allow setup of irq_info to fail David Vrabel
2013-08-09 18:15 ` [PATCH 09/12] xen/events: add a evtchn_op for port setup David Vrabel
2013-08-09 18:15 ` [PATCH 10/12] xen/events: Refactor evtchn_to_irq array to be dynamically allocated David Vrabel
2013-08-09 18:15 ` [PATCH 11/12] xen/events: Add the hypervisor interface for the FIFO-based event channels David Vrabel
2013-08-09 18:15 ` [PATCH 12/12] xen/events: use the FIFO-based ABI if available David Vrabel
2013-08-16 17:47 ` Wei Liu
2013-08-19 11:55 ` David Vrabel [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-03-19 21:04 [PATCH RFC 0/12] Linux: FIFO-based event channel ABI David Vrabel
2013-03-19 21:04 ` [PATCH 12/12] xen/events: use the FIFO-based ABI if available David Vrabel
2013-03-20 9:38 ` Roger Pau Monné
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