From: "Durrant, Paul" <pdurrant@amazon.co.uk> To: "Roger Pau Monné" <roger.pau@citrix.com> 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 09:56:54 +0000 [thread overview] Message-ID: <5ddf980a3fba4fb39571184e688cefc5@EX13D32EUC003.ant.amazon.com> (raw) In-Reply-To: <20200221092219.GU4679@Air-de-Roger> > -----Original Message----- > From: Roger Pau Monné <roger.pau@citrix.com> > Sent: 21 February 2020 09:22 > To: Durrant, Paul <pdurrant@amazon.co.uk> > Cc: Agarwal, Anchal <anchalag@amazon.com>; Valentin, Eduardo > <eduval@amazon.com>; len.brown@intel.com; peterz@infradead.org; > benh@kernel.crashing.org; x86@kernel.org; linux-mm@kvack.org; > pavel@ucw.cz; hpa@zytor.com; tglx@linutronix.de; sstabellini@kernel.org; > fllinden@amaozn.com; Kamata, Munehisa <kamatam@amazon.com>; > mingo@redhat.com; xen-devel@lists.xenproject.org; Singh, Balbir > <sblbir@amazon.com>; axboe@kernel.dk; konrad.wilk@oracle.com; > bp@alien8.de; boris.ostrovsky@oracle.com; jgross@suse.com; > netdev@vger.kernel.org; linux-pm@vger.kernel.org; rjw@rjwysocki.net; > linux-kernel@vger.kernel.org; vkuznets@redhat.com; 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 > > 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. What about writing the suspend image itself? Normal filesystem I/O will have been flushed of course, but whatever vestigial kernel actually writes out the hibernation file may well expect a final D0->D3 on the storage device to cause a flush. Again, I don't know the specifics for Linux (and Windows actually uses an incarnation of the crash kernel to do the job, which brings with it a whole other set of complexity as far as PV drivers go). Paul > > Thanks, Roger.
WARNING: multiple messages have this Message-ID (diff)
From: "Durrant, Paul" <pdurrant@amazon.co.uk> To: "Roger Pau Monné" <roger.pau@citrix.com> Cc: "Valentin, Eduardo" <eduval@amazon.com>, "peterz@infradead.org" <peterz@infradead.org>, "benh@kernel.crashing.org" <benh@kernel.crashing.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.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>, "x86@kernel.org" <x86@kernel.org>, "mingo@redhat.com" <mingo@redhat.com>, "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>, "Singh, Balbir" <sblbir@amazon.com>, "len.brown@intel.com" <len.brown@intel.com>, "jgross@suse.com" <jgross@suse.com>, "konrad.wilk@oracle.com" <konrad.wilk@oracle.com>, "Agarwal, Anchal" <anchalag@amazon.com>, "bp@alien8.de" <bp@alien8.de>, "boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>, "axboe@kernel.dk" <axboe@kernel.dk>, "netdev@vger.kernel.org" <netdev@vger.kernel.org>, "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>, "rjw@rjwysocki.net" <rjw@rjwysocki.net>, "Kamata, Munehisa" <kamatam@amazon.com>, "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 09:56:54 +0000 [thread overview] Message-ID: <5ddf980a3fba4fb39571184e688cefc5@EX13D32EUC003.ant.amazon.com> (raw) In-Reply-To: <20200221092219.GU4679@Air-de-Roger> > -----Original Message----- > From: Roger Pau Monné <roger.pau@citrix.com> > Sent: 21 February 2020 09:22 > To: Durrant, Paul <pdurrant@amazon.co.uk> > Cc: Agarwal, Anchal <anchalag@amazon.com>; Valentin, Eduardo > <eduval@amazon.com>; len.brown@intel.com; peterz@infradead.org; > benh@kernel.crashing.org; x86@kernel.org; linux-mm@kvack.org; > pavel@ucw.cz; hpa@zytor.com; tglx@linutronix.de; sstabellini@kernel.org; > fllinden@amaozn.com; Kamata, Munehisa <kamatam@amazon.com>; > mingo@redhat.com; xen-devel@lists.xenproject.org; Singh, Balbir > <sblbir@amazon.com>; axboe@kernel.dk; konrad.wilk@oracle.com; > bp@alien8.de; boris.ostrovsky@oracle.com; jgross@suse.com; > netdev@vger.kernel.org; linux-pm@vger.kernel.org; rjw@rjwysocki.net; > linux-kernel@vger.kernel.org; vkuznets@redhat.com; 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 > > 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. What about writing the suspend image itself? Normal filesystem I/O will have been flushed of course, but whatever vestigial kernel actually writes out the hibernation file may well expect a final D0->D3 on the storage device to cause a flush. Again, I don't know the specifics for Linux (and Windows actually uses an incarnation of the crash kernel to do the job, which brings with it a whole other set of complexity as far as PV drivers go). Paul > > Thanks, Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2020-02-21 9:57 UTC|newest] Thread overview: 73+ 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 23:21 ` [Xen-devel] " 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 23:22 ` [Xen-devel] " 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 ` [Xen-devel] " 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 23:23 ` [Xen-devel] " 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 ` [Xen-devel] " 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 23:24 ` [Xen-devel] " Anchal Agarwal 2020-02-14 23:25 ` [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal 2020-02-14 23:25 ` [Xen-devel] " Anchal Agarwal 2020-02-17 10:05 ` Roger Pau Monné 2020-02-17 10:05 ` [Xen-devel] " Roger Pau Monné 2020-02-17 23:05 ` Anchal Agarwal 2020-02-17 23:05 ` [Xen-devel] " Anchal Agarwal 2020-02-18 9:16 ` Roger Pau Monné 2020-02-18 9:16 ` [Xen-devel] " Roger Pau Monné 2020-02-19 18:04 ` Anchal Agarwal 2020-02-19 18:04 ` [Xen-devel] " Anchal Agarwal 2020-02-20 8:39 ` Roger Pau Monné 2020-02-20 8:39 ` [Xen-devel] " Roger Pau Monné 2020-02-20 8:54 ` Durrant, Paul 2020-02-20 8:54 ` Durrant, Paul 2020-02-20 15:45 ` Roger Pau Monné 2020-02-20 15:45 ` Roger Pau Monné 2020-02-20 16:23 ` Durrant, Paul 2020-02-20 16:23 ` Durrant, Paul 2020-02-20 16:48 ` Roger Pau Monné 2020-02-20 16:48 ` Roger Pau Monné 2020-02-20 17:01 ` Durrant, Paul 2020-02-20 17:01 ` Durrant, Paul 2020-02-21 0:49 ` Anchal Agarwal 2020-02-21 0:49 ` Anchal Agarwal 2020-02-21 9:47 ` Roger Pau Monné 2020-02-21 9:47 ` Roger Pau Monné 2020-02-21 9:22 ` Roger Pau Monné 2020-02-21 9:22 ` Roger Pau Monné 2020-02-21 9:56 ` Durrant, Paul [this message] 2020-02-21 9:56 ` Durrant, Paul 2020-02-21 10:21 ` Roger Pau Monné 2020-02-21 10:21 ` Roger Pau Monné 2020-02-21 10:33 ` Durrant, Paul 2020-02-21 10:33 ` Durrant, Paul 2020-02-21 11:51 ` Roger Pau Monné 2020-02-21 11:51 ` Roger Pau Monné 2020-02-21 14:24 ` Roger Pau Monné 2020-02-21 14:24 ` [Xen-devel] " Roger Pau Monné 2020-03-06 18:40 ` Anchal Agarwal 2020-03-06 18:40 ` [Xen-devel] " Anchal Agarwal 2020-03-09 9:54 ` Roger Pau Monné 2020-03-09 9:54 ` [Xen-devel] " 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 2020-03-13 17:21 ` [Xen-devel] " Anchal Agarwal 2020-02-14 23:25 ` [RFC PATCH v3 07/12] genirq: Shutdown irq chips in suspend/resume during hibernation Anchal Agarwal 2020-02-14 23:25 ` [Xen-devel] " Anchal Agarwal 2020-03-06 23:03 ` Thomas Gleixner 2020-03-06 23:03 ` [Xen-devel] " Thomas Gleixner 2020-03-09 22:37 ` [EXTERNAL][RFC " Anchal Agarwal 2020-03-09 22:37 ` [Xen-devel] " 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 23:26 ` [Xen-devel] [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 ` [Xen-devel] " 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 ` [Xen-devel] " 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 23:27 ` [Xen-devel] " 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 2020-02-14 23:28 ` [Xen-devel] " Anchal Agarwal -- strict thread matches above, loose matches on Subject: below -- 2020-02-12 22:32 [Xen-devel] [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal
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