From: "Longpeng (Mike)" <longpeng2@huawei.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>
Cc: <qemu-devel@nongnu.org>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
"Longpeng(Mike)" <longpeng.mike@gmail.com>,
Gonglei <arei.gonglei@huawei.com>,
Huangzhichao <huangzhichao@huawei.com>
Subject: Re: vfio_pin_map_dma cause synchronize_sched wait too long
Date: Mon, 2 Dec 2019 17:42:13 +0800 [thread overview]
Message-ID: <561fb205-16be-ae87-9cfe-61e6a3b04dc5@huawei.com> (raw)
In-Reply-To: <34c53520-4144-fe71-528a-8df53e7f4dd1@redhat.com>
在 2019/12/2 17:31, Paolo Bonzini 写道:
> On 02/12/19 10:10, Longpeng (Mike) wrote:
>>
>> Suppose there're two VMs: VM1 is bind to node-0 and calling vfio_pin_map_dma(),
>> VM2 is a migrate incoming VM which bind to node-1. We found the vm_start( QEMU
>> function) of VM2 will take too long occasionally, the reason is as follow.
>
> Which part of vfio_pin_map_dma is running? There is already a
I need more analysis to find which part.
> cond_resched in vfio_iommu_map. Perhaps you could add one to
> vfio_pin_pages_remote and/or use vfio_pgsize_bitmap to cap the number of
> pages that it returns.
Um ... There's only one running task (qemu-kvm of the VM1) on that CPU, so maybe
the cond_resched() is ineffective ?
> > Paolo
>
>
>
--
Regards,
Longpeng(Mike)
WARNING: multiple messages have this Message-ID (diff)
From: "Longpeng (Mike)" <longpeng2@huawei.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org,
linux-kernel@vger.kernel.org, Gonglei <arei.gonglei@huawei.com>,
Huangzhichao <huangzhichao@huawei.com>,
"Longpeng\(Mike\)" <longpeng.mike@gmail.com>
Subject: Re: vfio_pin_map_dma cause synchronize_sched wait too long
Date: Mon, 2 Dec 2019 17:42:13 +0800 [thread overview]
Message-ID: <561fb205-16be-ae87-9cfe-61e6a3b04dc5@huawei.com> (raw)
In-Reply-To: <34c53520-4144-fe71-528a-8df53e7f4dd1@redhat.com>
在 2019/12/2 17:31, Paolo Bonzini 写道:
> On 02/12/19 10:10, Longpeng (Mike) wrote:
>>
>> Suppose there're two VMs: VM1 is bind to node-0 and calling vfio_pin_map_dma(),
>> VM2 is a migrate incoming VM which bind to node-1. We found the vm_start( QEMU
>> function) of VM2 will take too long occasionally, the reason is as follow.
>
> Which part of vfio_pin_map_dma is running? There is already a
I need more analysis to find which part.
> cond_resched in vfio_iommu_map. Perhaps you could add one to
> vfio_pin_pages_remote and/or use vfio_pgsize_bitmap to cap the number of
> pages that it returns.
Um ... There's only one running task (qemu-kvm of the VM1) on that CPU, so maybe
the cond_resched() is ineffective ?
> > Paolo
>
>
>
--
Regards,
Longpeng(Mike)
next prev parent reply other threads:[~2019-12-02 9:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 9:10 vfio_pin_map_dma cause synchronize_sched wait too long Longpeng (Mike)
2019-12-02 9:10 ` Longpeng (Mike)
2019-12-02 9:31 ` Paolo Bonzini
2019-12-02 9:31 ` Paolo Bonzini
2019-12-02 9:42 ` Longpeng (Mike) [this message]
2019-12-02 9:42 ` Longpeng (Mike)
2019-12-02 10:06 ` Paolo Bonzini
2019-12-02 10:06 ` Paolo Bonzini
2019-12-02 10:47 ` Longpeng (Mike)
2019-12-02 10:47 ` Longpeng (Mike)
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