Linux-PM Archive on lore.kernel.org
 help / color / Atom feed
From: "Roger Pau Monné" <roger.pau@citrix.com>
To: "Durrant, Paul" <pdurrant@amazon.co.uk>
Cc: "Agarwal, Anchal" <anchalag@amazon.com>,
	"Valentin, Eduardo" <eduval@amazon.com>,
	"len.brown@intel.com" <len.brown@intel.com>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"pavel@ucw.cz" <pavel@ucw.cz>, "hpa@zytor.com" <hpa@zytor.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>,
	"fllinden@amaozn.com" <fllinden@amaozn.com>,
	"Kamata, Munehisa" <kamatam@amazon.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"Singh, Balbir" <sblbir@amazon.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"bp@alien8.de" <bp@alien8.de>,
	"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
	"jgross@suse.com" <jgross@suse.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"Woodhouse, David" <dwmw@amazon.co.uk>
Subject: Re: [Xen-devel] [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation
Date: Fri, 21 Feb 2020 10:22:19 +0100
Message-ID: <20200221092219.GU4679@Air-de-Roger> (raw)
In-Reply-To: <e42fa35800f04b6f953e4af87f2c1a02@EX13D32EUC003.ant.amazon.com>

On Thu, Feb 20, 2020 at 05:01:52PM +0000, Durrant, Paul wrote:
> > > Hopefully what I said above illustrates why it may not be 100% common.
> > 
> > Yes, that's fine. I don't expect it to be 100% common (as I guess
> > that the hooks will have different prototypes), but I expect
> > that routines can be shared, and that the approach taken can be the
> > same.
> > 
> > For example one necessary difference will be that xenbus initiated
> > suspend won't close the PV connection, in case suspension fails. On PM
> > suspend you seem to always close the connection beforehand, so you
> > will always have to re-negotiate on resume even if suspension failed.
> > 
> > What I'm mostly worried about is the different approach to ring
> > draining. Ie: either xenbus is changed to freeze the queues and drain
> > the shared rings, or PM uses the already existing logic of not
> > flushing the rings an re-issuing in-flight requests on resume.
> > 
> 
> Yes, that's needs consideration. I don’t think the same semantic can be suitable for both. E.g. in a xen-suspend we need to freeze with as little processing as possible to avoid dirtying RAM late in the migration cycle, and we know that in-flight data can wait. But in a transition to S4 we need to make sure that at least all the in-flight blkif requests get completed, since they probably contain bits of the guest's memory image and that's not going to get saved any other way.

Thanks, that makes sense and something along this lines should be
added to the commit message IMO.

Wondering about S4, shouldn't we expect the queues to already be
empty? As any subsystem that wanted to store something to disk should
make sure requests have been successfully completed before
suspending.

Thanks, Roger.

  parent reply index

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14 23:21 [RFC RESEND PATCH v3 00/12] Enable PM hibernation on guest VMs Anchal Agarwal
2020-02-14 23:22 ` [RFC PATCH v3 01/12] xen/manage: keep track of the on-going suspend mode Anchal Agarwal
2020-02-14 23:23 ` [RFC PATCH v3 02/12] xenbus: add freeze/thaw/restore callbacks support Anchal Agarwal
2020-02-14 23:23 ` [RFC PATCH v3 03/12] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume Anchal Agarwal
2020-02-14 23:24 ` [RFC PATCH v3 04/12] x86/xen: add system core suspend and resume callbacks Anchal Agarwal
2020-02-14 23:24 ` [RFC PATCH v3 05/12] xen-netfront: add callbacks for PM suspend and hibernation support Anchal Agarwal
2020-02-14 23:25 ` [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal
2020-02-17 10:05   ` Roger Pau Monné
2020-02-17 23:05     ` Anchal Agarwal
2020-02-18  9:16       ` Roger Pau Monné
2020-02-19 18:04         ` Anchal Agarwal
2020-02-20  8:39           ` Roger Pau Monné
2020-02-20  8:54             ` [Xen-devel] " Durrant, Paul
2020-02-20 15:45               ` Roger Pau Monné
2020-02-20 16:23                 ` Durrant, Paul
2020-02-20 16:48                   ` Roger Pau Monné
2020-02-20 17:01                     ` Durrant, Paul
2020-02-21  0:49                       ` Anchal Agarwal
2020-02-21  9:47                         ` Roger Pau Monné
2020-02-21  9:22                       ` Roger Pau Monné [this message]
2020-02-21  9:56                         ` Durrant, Paul
2020-02-21 10:21                           ` Roger Pau Monné
2020-02-21 10:33                             ` Durrant, Paul
2020-02-21 11:51                               ` Roger Pau Monné
2020-02-21 14:24   ` Roger Pau Monné
2020-03-06 18:40     ` Anchal Agarwal
2020-03-09  9:54       ` Roger Pau Monné
     [not found]         ` <FA688A68-5372-4757-B075-A69A45671CB9@amazon.com>
     [not found]           ` <20200312090435.GK24449@Air-de-Roger.citrite.net>
2020-03-13 17:21             ` Anchal Agarwal
2020-02-14 23:25 ` [RFC PATCH v3 07/12] genirq: Shutdown irq chips in suspend/resume during hibernation Anchal Agarwal
2020-03-06 23:03   ` Thomas Gleixner
2020-03-09 22:37     ` [EXTERNAL][RFC " Anchal Agarwal
2020-02-14 23:26 ` [RFC PATCH v3 08/12] xen/time: introduce xen_{save,restore}_steal_clock Anchal Agarwal
2020-02-14 23:27 ` [RFC PATCH v3 09/12] x86/xen: save and restore steal clock Anchal Agarwal
2020-02-14 23:27 ` [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal
2020-02-14 23:27 ` [RFC PATCH v3 11/12] xen: Update sched clock offset to avoid system instability in hibernation Anchal Agarwal
2020-02-14 23:28 ` [RFC PATCH v3 12/12] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Anchal Agarwal

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200221092219.GU4679@Air-de-Roger \
    --to=roger.pau@citrix.com \
    --cc=anchalag@amazon.com \
    --cc=axboe@kernel.dk \
    --cc=benh@kernel.crashing.org \
    --cc=boris.ostrovsky@oracle.com \
    --cc=bp@alien8.de \
    --cc=davem@davemloft.net \
    --cc=dwmw@amazon.co.uk \
    --cc=eduval@amazon.com \
    --cc=fllinden@amaozn.com \
    --cc=hpa@zytor.com \
    --cc=jgross@suse.com \
    --cc=kamatam@amazon.com \
    --cc=konrad.wilk@oracle.com \
    --cc=len.brown@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=pavel@ucw.cz \
    --cc=pdurrant@amazon.co.uk \
    --cc=peterz@infradead.org \
    --cc=rjw@rjwysocki.net \
    --cc=sblbir@amazon.com \
    --cc=sstabellini@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=vkuznets@redhat.com \
    --cc=x86@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pm/0 linux-pm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pm linux-pm/ https://lore.kernel.org/linux-pm \
		linux-pm@vger.kernel.org
	public-inbox-index linux-pm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git