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From: Anchal Agarwal <anchalag@amazon.com>
To: <tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>,
	<hpa@zytor.com>, <x86@kernel.org>, <boris.ostrovsky@oracle.com>,
	<jgross@suse.com>, <linux-pm@vger.kernel.org>,
	<linux-mm@kvack.org>, <kamatam@amazon.com>,
	<sstabellini@kernel.org>, <konrad.wilk@oracle.com>,
	<roger.pau@citrix.com>, <axboe@kernel.dk>, <davem@davemloft.net>,
	<rjw@rjwysocki.net>, <len.brown@intel.com>, <pavel@ucw.cz>,
	<peterz@infradead.org>, <eduval@amazon.com>, <sblbir@amazon.com>,
	<anchalag@amazon.com>, <xen-devel@lists.xenproject.org>,
	<vkuznets@redhat.com>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <dwmw@amazon.co.uk>,
	<fllinden@amaozn.com>, <benh@kernel.crashing.org>
Subject: [RFC PATCH v3 11/12] xen: Update sched clock offset to avoid system instability in hibernation
Date: Fri, 14 Feb 2020 23:27:29 +0000
Message-ID: <feefc88bca88e910c2860f6fbcb85097c6528cc7.1581721799.git.anchalag@amazon.com> (raw)
In-Reply-To: <cover.1581721799.git.anchalag@amazon.com>

Save/restore xen_sched_clock_offset in syscore suspend/resume during PM
hibernation. Commit '867cefb4cb1012: ("xen: Fix x86 sched_clock() interface
for xen")' fixes xen guest time handling during migration. A similar issue
is seen during PM hibernation when system runs CPU intensive workload.
Post resume pvclock resets the value to 0 however, xen sched_clock_offset
is never updated. System instability is seen during resume from hibernation
when system is under heavy CPU load. Since xen_sched_clock_offset is not
updated, system does not see the monotonic clock value and the scheduler
would then think that heavy CPU hog tasks need more time in CPU, causing
the system to freeze

Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
---
 arch/x86/xen/suspend.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index dae0f74f5390..7e5275944810 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -105,6 +105,8 @@ static int xen_syscore_suspend(void)
 		xen_save_steal_clock(cpu);
 	}
 
+	xen_save_sched_clock_offset();
+
 	xrfp.domid = DOMID_SELF;
 	xrfp.gpfn = __pa(HYPERVISOR_shared_info) >> PAGE_SHIFT;
 
@@ -126,6 +128,12 @@ static void xen_syscore_resume(void)
 
 	pvclock_resume();
 
+	/*
+	 * Restore xen_sched_clock_offset during resume to maintain
+	 * monotonic clock value
+	 */
+	xen_restore_sched_clock_offset();
+
 	/* Nonboot CPUs will be resumed when they're brought up */
 	xen_restore_steal_clock(smp_processor_id());
 
-- 
2.24.1.AMZN


  parent reply index

Thread overview: 32+ 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
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
2020-02-14 23:25 ` [RFC PATCH v3 07/12] genirq: Shutdown irq chips in suspend/resume during hibernation 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 ` Anchal Agarwal [this message]
2020-02-14 23:28 ` [RFC PATCH v3 12/12] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Anchal Agarwal
  -- strict thread matches above, loose matches on Subject: below --
2020-02-12 22:35 [RFC PATCH v3 11/12] xen: Update sched clock offset to avoid system instability in hibernation Anchal Agarwal

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