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From: Wei Liu <wei.liu2@citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Lars Kurth <lars.kurth@citrix.com>,
	Changlong Xie <xiecl.fnst@cn.fujitsu.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	Wen Congyang <wency@cn.fujitsu.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Jiang Yunhong <yunhong.jiang@intel.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>,
	xen devel <xen-devel@lists.xen.org>,
	Anthony Perard <anthony.perard@citrix.com>,
	Dong Eddie <eddie.dong@intel.com>,
	Gui Jianfeng <guijianfeng@cn.fujitsu.com>,
	Shriram Rajagopalan <rshriram@cs.ubc.ca>,
	Yang Hongyang <hongyang.yang@easystack.cn>
Subject: Re: [PATCH v11 20/27] Support colo mode for qemu disk
Date: Wed, 9 Mar 2016 16:55:00 +0000	[thread overview]
Message-ID: <20160309165500.GD31271@citrix.com> (raw)
In-Reply-To: <20160309020920.GA5489@localhost.localdomain>

On Tue, Mar 08, 2016 at 09:09:20PM -0500, Konrad Rzeszutek Wilk wrote:
> > Furthermore, I think coming up with a story for PV-aware guests (PVHVM,
> > PV and PVH) is also non-trivial. For one the disk replication logic is
> 
> Pls keep in mind that PV guests can use QEMU qdisk if they wish.
> 

Oh right, I somehow talked myself into thinking blkback only.

> This is more of 'phy' vs 'file' question.
> > not implemented in PV block backend,  we're not sure how feasible to
> > replicate thing in QEMU into kernel, but we're quite sure it is not
> > going to be trivial technically and politically. The uncertainty is too
> 
> .. and I think doing it in the kernel is not a good idea. With PVH
> coming as the initial domain - we will now have solved the @$@#@@
> syscall bounce to hypervisor slowpath - which means that any libaio
> operations QEMU does on a file - which ends up going to the kernel
> with a syscall - will happen without incuring a huge context switch!
> 
> In other words the speed difference between qdisk and xen-blkback
> will now be just the syscall + aio code + fs overhead.
> 
> With proper batching this can be made faster*.
> 
> *: I am ignoring the other issues such as grant unmap in PVH guests
> and qdisk being quite spartan in features compared to xen-blkback.
> 

So now we do have a tangible story for PV-aware guest for disk
replication (note, other hindrance such as ckeckpointing the kernel in a
fast enough pace still needs to be solved) -- to use qdisk backend. That
means the current interfaces should be sufficient.

Wei.

> > big to come up with a clear idea what it would look like.

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  reply	other threads:[~2016-03-09 16:55 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-04  8:41 [PATCH v11 00/27] COarse-grain LOck-stepping Virtual Machines for Non-stop Service Changlong Xie
2016-03-04  8:41 ` [PATCH v11 01/27] tools/libxl: introduction of libxl__qmp_restore to load qemu state Changlong Xie
2016-03-04 16:30   ` Ian Jackson
2016-03-14  9:03     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 02/27] tools/libxl: introduce libxl__domain_common_switch_qemu_logdirty() Changlong Xie
2016-03-04  8:41 ` [PATCH v11 03/27] tools/libxl: Add back channel to allow migration target send data back Changlong Xie
2016-03-04 16:38   ` Ian Jackson
2016-03-08 16:38     ` Wei Liu
2016-03-17  8:07     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 04/27] tools/libxl: Introduce new helper function dup_fd_helper() Changlong Xie
2016-03-04 16:42   ` Ian Jackson
2016-03-17  8:08     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 05/27] tools/libx{l, c}: add back channel to libxc Changlong Xie
2016-03-04 16:45   ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 06/27] docs: add colo readme Changlong Xie
2016-03-04  8:41 ` [PATCH v11 07/27] docs/libxl: Introduce CHECKPOINT_CONTEXT to support migration v2 colo streams Changlong Xie
2016-03-04 16:51   ` Ian Jackson
2016-03-08 16:38     ` Wei Liu
2016-03-11  7:13     ` Wen Congyang
2016-03-04  8:41 ` [PATCH v11 08/27] libxc/migration: Specification update for DIRTY_PFN_LIST records Changlong Xie
2016-03-04 16:53   ` Ian Jackson
2016-03-17  8:10     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 09/27] libxc/migration: export read_record for common use Changlong Xie
2016-03-04 16:55   ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 10/27] tools/libxl: add back channel support to write stream Changlong Xie
2016-03-04 17:00   ` Ian Jackson
2016-03-07  2:13     ` Wen Congyang
2016-03-11  9:05     ` Wen Congyang
2016-03-17  8:11     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 11/27] tools/libxl: add back channel support to read stream Changlong Xie
2016-03-04 17:01   ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 12/27] tools/libx{l, c}: introduce wait_checkpoint callback Changlong Xie
2016-03-04 17:03   ` Ian Jackson
2016-03-04 20:23     ` Konrad Rzeszutek Wilk
2016-03-07  2:16       ` Wen Congyang
2016-03-17  8:16     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 13/27] tools/libx{l, c}: add postcopy/suspend callback to restore side Changlong Xie
2016-03-04 17:05   ` Ian Jackson
2016-03-17  8:17     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 14/27] secondary vm suspend/resume/checkpoint code Changlong Xie
2016-03-04 17:11   ` Ian Jackson
2016-03-07  2:57     ` Wen Congyang
2016-03-17  9:03     ` Changlong Xie
2016-03-17 12:19       ` Wei Liu
2016-03-04  8:41 ` [PATCH v11 15/27] primary " Changlong Xie
2016-03-04 17:14   ` Ian Jackson
2016-03-07  2:59     ` Wen Congyang
2016-03-04  8:41 ` [PATCH v11 16/27] libxc/restore: support COLO restore Changlong Xie
2016-03-04 17:16   ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 17/27] libxc/save: support COLO save Changlong Xie
2016-03-04 17:18   ` Ian Jackson
2016-03-07  3:00     ` Wen Congyang
2016-03-04  8:41 ` [PATCH v11 18/27] implement the cmdline for COLO Changlong Xie
2016-03-04 17:22   ` Ian Jackson
2016-03-07  3:04     ` Wen Congyang
2016-03-04  8:41 ` [PATCH v11 19/27] COLO: introduce new API to prepare/start/do/get_error/stop replication Changlong Xie
2016-03-04 17:26   ` Ian Jackson
2016-03-08 16:46     ` Wei Liu
2016-03-18  3:44     ` Changlong Xie
2016-03-18 11:35       ` Wei Liu
2016-03-18  3:45     ` Changlong Xie
2016-03-04 17:29   ` Ian Jackson
2016-03-18  3:49     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 20/27] Support colo mode for qemu disk Changlong Xie
2016-03-04 17:44   ` Ian Jackson
2016-03-07  2:06     ` Wen Congyang
2016-03-17 17:18       ` Ian Jackson
2016-03-18  5:42         ` Wen Congyang
2016-03-04 17:52   ` Ian Jackson
2016-03-04 20:30     ` Konrad Rzeszutek Wilk
2016-03-07  2:10       ` Wen Congyang
2016-03-08 17:22         ` Wei Liu
2016-03-09  2:09           ` Konrad Rzeszutek Wilk
2016-03-09 16:55             ` Wei Liu [this message]
2016-03-17 17:09           ` Ian Jackson
2016-03-17 17:10       ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 21/27] COLO: use qemu block replication Changlong Xie
2016-03-04  8:41 ` [PATCH v11 22/27] COLO proxy: implement setup/teardown of COLO proxy module Changlong Xie
2016-03-04 17:59   ` Ian Jackson
2016-03-18  8:22     ` Changlong Xie
2016-03-22  5:44     ` Changlong Xie
2016-03-22  5:55       ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 23/27] COLO proxy: preresume, postresume and checkpoint Changlong Xie
2016-03-04 18:01   ` Ian Jackson
2016-03-18  8:20     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 24/27] COLO nic: implement COLO nic subkind Changlong Xie
2016-03-04 18:02   ` Ian Jackson
2016-03-18  8:20     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 25/27] setup and control colo proxy on primary side Changlong Xie
2016-03-04 18:05   ` Ian Jackson
2016-03-22  6:01     ` Changlong Xie
2016-03-04  8:41 ` [PATCH v11 26/27] setup and control colo proxy on secondary side Changlong Xie
2016-03-04 18:05   ` Ian Jackson
2016-03-04  8:41 ` [PATCH v11 27/27] cmdline switches and config vars to control colo-proxy Changlong Xie
2016-03-04 18:09   ` Ian Jackson
2016-03-22  4:13     ` Changlong Xie
2016-03-04 18:17 ` [PATCH v11 00/27] COarse-grain LOck-stepping Virtual Machines for Non-stop Service Ian Jackson
2016-03-04 20:35   ` Konrad Rzeszutek Wilk
2016-03-17 17:19     ` Ian Jackson
2016-03-17 17:41   ` Ian Jackson

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