[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes. |
Date: |
Mon, 18 Mar 2013 19:00:14 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 |
Il 18/03/2013 18:38, George Dunlap ha scritto:
>>>
>> This might be a difference between Xen and KVM. On Xen migration is
>> made to a server in a paused state, and it's only unpaused when
>> the migration to B is complete. There's a sort of extra handshake at
>> the end.
>
> I think what you mean is that all the memory is handled by Xen and the
> toolstack, not by qemu. The qemu state is sent as the very last thing,
> after all of the memory, and therefore (you are arguing) that qemu is
> not started, and the files cannot be opened, until after the migration
> is nearly complete, and certainly until after the file is closed on the
> sending side.
That would be quite dangerous. Files aren't closed until after QEMU
exits; at this point whatever problem you have launching QEMU on the
destination would be unrecoverable.
Even for successful migration, it would also be bad for downtime (QEMU
isn't exactly lightning-fast to start). And even if failure weren't
catastrophic, it would be a pity to transfer a few gigs of memory and
then find out that QEMU isn't present in the destination. :)
Still, it's more than possible that I've forgotten something about Xen's
management of QEMU.
> (In KVM this isn't the case because I assume it's qemu that handles the
> memory transition, and so it is likely to open the files on the
> receiving side when the migration starts.)
Yup.
Paolo
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., (continued)
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/18
- Re: [Qemu-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes.,
Paolo Bonzini <=
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Paolo Bonzini, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Alex Bligh, 2013/03/19
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., Stefano Stabellini, 2013/03/20
- Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes., George Dunlap, 2013/03/20