From: Asias He <asias.hejun@gmail.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>, Cyrill Gorcunov <gorcunov@gmail.com>,
Sasha Levin <levinsasha928@gmail.com>,
Prasad Joshi <prasadjoshi124@gmail.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH 3/3] kvm tools: Make virtio-blk kvm__irq_line thread safe
Date: Fri, 29 Apr 2011 15:26:20 +0800 [thread overview]
Message-ID: <4DBA681C.4090707@gmail.com> (raw)
In-Reply-To: <BANLkTik_wXBA+4X-BRE_H-yUEkbSTcOt5A@mail.gmail.com>
On 04/29/2011 02:55 PM, Pekka Enberg wrote:
> On Fri, Apr 29, 2011 at 9:44 AM, Ingo Molnar <mingo@elte.hu> wrote:
>> Hm, this looks a bit strange (the mutex here protects only a kernel call - that
>> cannot be right) and there's no explanation why it's needed. Why do
>> VIRTIO_BLK_IRQ (== KVM_IRQ_LINE ioctl()) calls have to be covered by the mutex?
>>
>> A short blurb about expected behavior on SMP and locking rules at the top of
>> virtio-blk.c would be nice.
>
> Yes, looks strange. Asias, did you see some bad behavior that this
> fixes?
Yes. I see random virtio net hangs with scp test. This commit
847838c573f4c04be7547f508a99be2dfdefb4fd triggers this problem as we are
using separte irq lines for each virtio devices instead of sharing one
irq line for all virtio devices.
> The per-device mutexes are there to protect device state. The
> assumption here is that KVM handles KVM_IRQ_LINE ioctl() serialization
> by titself.
--
Best Regards,
Asias He
next prev parent reply other threads:[~2011-04-29 7:27 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-29 6:36 [PATCH 1/3] kvm tools: Make virtio-net kvm__irq_line thread safe Asias He
2011-04-29 6:36 ` [PATCH 2/3] kvm tools: Make virtio-console " Asias He
2011-04-29 6:44 ` Ingo Molnar
2011-04-29 6:36 ` [PATCH 3/3] kvm tools: Make virtio-blk " Asias He
2011-04-29 6:44 ` Ingo Molnar
2011-04-29 6:55 ` Pekka Enberg
2011-04-29 7:26 ` Asias He [this message]
2011-04-29 7:55 ` Pekka Enberg
2011-04-29 8:29 ` Sasha Levin
2011-04-29 6:46 ` [PATCH 1/3] kvm tools: Make virtio-net " Ingo Molnar
2011-04-29 6:52 ` Pekka Enberg
2011-04-29 7:13 ` Asias He
2011-04-29 7:15 ` Pekka Enberg
2011-04-29 7:38 ` Asias He
2011-04-29 7:45 ` Ingo Molnar
2011-04-29 7:53 ` Sasha Levin
2011-04-29 10:02 ` Cyrill Gorcunov
2011-04-29 10:37 ` Pekka Enberg
2011-04-29 10:47 ` Cyrill Gorcunov
2011-04-29 10:22 ` Ingo Molnar
2011-04-29 16:52 ` Sasha Levin
2011-04-29 20:39 ` Ingo Molnar
2011-04-29 7:30 ` Ingo Molnar
2011-04-29 7:47 ` Asias He
2011-04-29 10:32 ` Ingo Molnar
2011-04-29 10:42 ` Pekka Enberg
2011-04-29 17:43 ` Pekka Enberg
2011-04-29 19:59 ` Ingo Molnar
2011-04-30 7:44 ` Pekka Enberg
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