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Date: Tue, 8 Mar 2011 22:50:49 +0100
From: Daniel Kiper <dkiper@...-space.pl>
To: ian.campbell@...rix.com, akpm@...ux-foundation.org,
andi.kleen@...el.com, haicheng.li@...ux.intel.com,
fengguang.wu@...el.com, jeremy@...p.org, konrad.wilk@...cle.com,
dan.magenheimer@...cle.com, v.tolstov@...fip.ru, pasik@....fi,
dave@...ux.vnet.ibm.com, wdauchy@...il.com, rientjes@...gle.com,
xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: [PATCH R4 7/7] xen/balloon: Memory hotplug support for Xen balloon driver
Memory hotplug support for Xen balloon driver. It should be
mentioned that hotplugged memory is not onlined automatically.
It should be onlined by user through standard sysfs interface.
Signed-off-by: Daniel Kiper <dkiper@...-space.pl>
---
drivers/xen/Kconfig | 10 +++
drivers/xen/balloon.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 159 insertions(+), 5 deletions(-)
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 07bec09..8f880aa 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -9,6 +9,16 @@ config XEN_BALLOON
the system to expand the domain's memory allocation, or alternatively
return unneeded memory to the system.
+config XEN_BALLOON_MEMORY_HOTPLUG
+ bool "Memory hotplug support for Xen balloon driver"
+ default n
+ depends on XEN_BALLOON && MEMORY_HOTPLUG
+ help
+ Memory hotplug support for Xen balloon driver allows expanding memory
+ available for the system above limit declared at system startup.
+ It is very useful on critical systems which require long
+ run without rebooting.
+
config XEN_SCRUB_PAGES
bool "Scrub pages before returning them to system"
depends on XEN_BALLOON
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 431e9f0..3dc8a83 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -6,6 +6,12 @@
* Copyright (c) 2003, B Dragovic
* Copyright (c) 2003-2004, M Williamson, K Fraser
* Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ *
+ * Memory hotplug support was written by Daniel Kiper. Work on
+ * it was sponsored by Google under Google Summer of Code 2010
+ * program. Jeremy Fitzhardinge from Xen.org was the mentor for
+ * this project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@@ -44,6 +50,9 @@
#include <linux/list.h>
#include <linux/sysdev.h>
#include <linux/gfp.h>
+#include <linux/notifier.h>
+#include <linux/memory.h>
+#include <linux/memory_hotplug.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
@@ -93,6 +102,10 @@ struct balloon_stats {
unsigned long max_schedule_delay;
unsigned long retry_count;
unsigned long max_retry_count;
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ unsigned long hotplug_pages;
+ unsigned long balloon_hotplug;
+#endif
};
static DEFINE_MUTEX(balloon_mutex);
@@ -221,7 +234,93 @@ static enum bp_state update_schedule(enum bp_state state)
return BP_EAGAIN;
}
-static unsigned long current_target(void)
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static long current_credit(void)
+{
+ return balloon_stats.target_pages - balloon_stats.current_pages -
+ balloon_stats.hotplug_pages;
+}
+
+static int balloon_is_inflated(void)
+{
+ if (balloon_stats.balloon_low || balloon_stats.balloon_high ||
+ balloon_stats.balloon_hotplug)
+ return 1;
+ else
+ return 0;
+}
+
+static enum bp_state reserve_additional_memory(long credit)
+{
+ int rc;
+ unsigned long balloon_hotplug = credit;
+
+ balloon_hotplug <<= PAGE_SHIFT;
+
+ rc = add_virtual_memory((u64 *)&balloon_hotplug);
+
+ if (rc) {
+ pr_info("xen_balloon: %s: add_virtual_memory() failed: %i\n", __func__, rc);
+ return BP_EAGAIN;
+ }
+
+ balloon_hotplug >>= PAGE_SHIFT;
+
+ balloon_hotplug -= credit;
+
+ balloon_stats.hotplug_pages += credit;
+ balloon_stats.balloon_hotplug = balloon_hotplug;
+
+ return BP_DONE;
+}
+
+static int xen_online_page_notifier(struct notifier_block *nb, unsigned long val, void *v)
+{
+ struct page *page = v;
+ unsigned long pfn = page_to_pfn(page);
+
+ if (pfn >= num_physpages)
+ num_physpages = pfn + 1;
+
+ inc_totalhigh_pages();
+
+#ifdef CONFIG_FLATMEM
+ max_mapnr = max(pfn, max_mapnr);
+#endif
+
+ mutex_lock(&balloon_mutex);
+
+ __balloon_append(page);
+
+ if (balloon_stats.hotplug_pages)
+ --balloon_stats.hotplug_pages;
+ else
+ --balloon_stats.balloon_hotplug;
+
+ mutex_unlock(&balloon_mutex);
+
+ return NOTIFY_STOP;
+}
+
+static struct notifier_block xen_online_page_nb = {
+ .notifier_call = xen_online_page_notifier,
+ .priority = 10
+};
+
+static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
+{
+ if (val == MEM_ONLINE)
+ schedule_delayed_work(&balloon_worker, 0);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block xen_memory_nb = {
+ .notifier_call = xen_memory_notifier,
+ .priority = 0
+};
+#else
+static long current_credit(void)
{
unsigned long target = balloon_stats.target_pages;
@@ -230,9 +329,24 @@ static unsigned long current_target(void)
balloon_stats.balloon_low +
balloon_stats.balloon_high);
- return target;
+ return target - balloon_stats.current_pages;
+}
+
+static int balloon_is_inflated(void)
+{
+ if (balloon_stats.balloon_low || balloon_stats.balloon_high)
+ return 1;
+ else
+ return 0;
}
+static enum bp_state reserve_additional_memory(long credit)
+{
+ balloon_stats.target_pages = balloon_stats.current_pages;
+ return BP_DONE;
+}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
+
static enum bp_state increase_reservation(unsigned long nr_pages)
{
int rc;
@@ -244,6 +358,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
.domid = DOMID_SELF
};
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) {
+ nr_pages = min(nr_pages, balloon_stats.balloon_hotplug);
+ balloon_stats.hotplug_pages += nr_pages;
+ balloon_stats.balloon_hotplug -= nr_pages;
+ return BP_DONE;
+ }
+#endif
+
if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list);
@@ -308,6 +431,15 @@ static enum bp_state decrease_reservation(unsigned long nr_pages)
.domid = DOMID_SELF
};
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ if (balloon_stats.hotplug_pages) {
+ nr_pages = min(nr_pages, balloon_stats.hotplug_pages);
+ balloon_stats.hotplug_pages -= nr_pages;
+ balloon_stats.balloon_hotplug += nr_pages;
+ return BP_DONE;
+ }
+#endif
+
if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list);
@@ -368,10 +500,14 @@ static void balloon_process(struct work_struct *work)
mutex_lock(&balloon_mutex);
do {
- credit = current_target() - balloon_stats.current_pages;
+ credit = current_credit();
- if (credit > 0)
- state = increase_reservation(credit);
+ if (credit > 0) {
+ if (balloon_is_inflated())
+ state = increase_reservation(credit);
+ else
+ state = reserve_additional_memory(credit);
+ }
if (credit < 0)
state = decrease_reservation(-credit);
@@ -458,6 +594,14 @@ static int __init balloon_init(void)
balloon_stats.retry_count = 1;
balloon_stats.max_retry_count = 16;
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ balloon_stats.hotplug_pages = 0;
+ balloon_stats.balloon_hotplug = 0;
+
+ register_online_page_notifier(&xen_online_page_nb);
+ register_memory_notifier(&xen_memory_nb);
+#endif
+
register_balloon(&balloon_sysdev);
/*
--
1.5.6.5
--
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