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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] GSoC 2010 - Memory hotplug support for Xen guests - third fully working version
Hi,
Here is the third version of memory hotplug support
for Xen guests patch. This one cleanly applies to
git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git
repository, xen/memory-hotplug head.
On Fri, Aug 06, 2010 at 04:03:18PM +0400, Vasiliy G Tolstov wrote:
[...]
> Testing on sles 11 sp1 and opensuse 11.3. On results - send e-mail..
Thx.
On Fri, Aug 06, 2010 at 12:34:08PM -0400, Konrad Rzeszutek Wilk wrote:
[...]
> > +static int allocate_additional_memory(unsigned long nr_pages)
> > +{
> > + long rc;
> > + resource_size_t r_min, r_size;
> > + struct resource *r;
> > + struct xen_memory_reservation reservation = {
> > + .address_bits = 0,
> > + .extent_order = 0,
> > + .domid = DOMID_SELF
> > + };
> > + unsigned long flags, i, pfn;
> > +
> > + if (nr_pages > ARRAY_SIZE(frame_list))
> > + nr_pages = ARRAY_SIZE(frame_list);
> > +
> > + spin_lock_irqsave(&balloon_lock, flags);
> > +
> > + if (!is_memory_resource_reserved()) {
> > +
> > + /*
> > + * Look for first unused memory region starting at page
> > + * boundary. Skip last memory section created at boot time
> > + * becuase it may contains unused memory pages with PG_reserved
> > + * bit not set (online_pages require PG_reserved bit set).
> > + */
> > +
> > + r = kzalloc(sizeof(struct resource), GFP_KERNEL);
>
> You are holding a spinlock here. Kzalloc can sleep
Thx. Fixed.
On Fri, Aug 06, 2010 at 10:42:48AM -0700, Jeremy Fitzhardinge wrote:
> > - PV on HVM mode is supported now; it was tested on
> > git://xenbits.xen.org/people/sstabellini/linux-pvhvm.git
> > repository, 2.6.34-pvhvm head,
>
> Good. I noticed you have some specific tests for "xen_pv_domain()" -
> are there many differences between pv and hvm?
No. Only those changes are needed where
xen_domain()/xen_pv_domain() is used.
> >>>+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
> >>>+static inline unsigned long current_target(void)
> >>>+{
> >>>+ return balloon_stats.target_pages;
> >>Why does this need its own version?
> >Because original version return values not bigger
> >then initial memory allocation which does not allow
> >memory hotplug to function.
>
> But surely they can be combined? A system without
> XEN_BALLOON_MEMORY_HOTPLUG is identical to a system with
> XEN_BALLOON_MEMORY_HOTPLUG which hasn't yet added any memory. Some
> variables may become constants (because memory can never be hot-added),
> but the logic of the code should be the same.
Done.
> Overall, this looks much better. The next step is to split this into at
> least two patches: one for the core code, and one for the Xen bits.
> Each patch should do just one logical operation, so if you have several
> distinct changes to the core code, put them in separate patches.
I will do that if this patch will be accepted.
> >diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> >index 38434da..beb1aa7 100644
> >--- a/arch/x86/Kconfig
> >+++ b/arch/x86/Kconfig
> >@@ -1273,7 +1273,7 @@ config ARCH_SELECT_MEMORY_MODEL
> > depends on ARCH_SPARSEMEM_ENABLE
> >
> > config ARCH_MEMORY_PROBE
> >- def_bool y
> >+ def_bool X86_64&& !XEN
> > depends on MEMORY_HOTPLUG
>
> The trouble with making anything statically depend on Xen at config time
> is that you lose it even if you're not running under Xen. A pvops
> kernel can run on bare hardware as well, and we don't want to lose
> functionality (assume that CONFIG_XEN is always set, since distros do
> always set it).
>
> Can you find a clean way to prevent/disable ARCH_MEMORY_PROBE at runtime
> when in a Xen context?
There is no simple way to do that. It requiers to do some
changes in drivers/base/memory.c code. I think it should
be done as kernel boot option (on by default to not break
things using this interface now). If it be useful for maintainers
of mm/memory_hotplug.c and drivers/base/memory.c code then
I could do that. Currently original arch/x86/Kconfig version
is restored.
> >+/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
> >*/
> >+static int __ref xen_add_memory(int nid, u64 start, u64 size)
>
> Could this be __meminit too then?
Good question. I looked throught the code and could
not find any simple explanation why mm/memory_hotplug.c
authors used __ref instead __meminit. Could you (mm/memory_hotplug.c
authors/maintainers) tell us why ???
> >+{
> >+ pg_data_t *pgdat = NULL;
> >+ int new_pgdat = 0, ret;
> >+
> >+ lock_system_sleep();
>
> What's this for? I see all its other users are in the memory hotplug
> code, but presumably they're concerned about a real S3 suspend. Do we
> care about that here?
Yes, because as I know S3 state is supported by Xen guests.
> Actually, this is nearly identical to mm/memory_hotplug.c:add_memory().
> It looks to me like you should:
>
> * pull the common core out into mm/memory_hotplug.c:__add_memory()
> (or a better name)
> * make add_memory() do its
> register_memory_resource()/firmware_map_add_hotplug() around that
> (assuming they're definitely unwanted in the Xen case)
> * make xen_add_memory() just call __add_memory() along with whatever
> else it needs (which is nothing?)
>
> That way you can export a high-level __add_memory function from
> memory_hotplug.c rather than the two internal detail functions.
Done.
> >+ r->name = "System RAM";
>
> How about making it clear its Xen hotplug RAM? Or do things care about
> the "System RAM" name?
As I know no however as I saw anybody do not differentiate between
normal and hotplugged memory. I thought about that ealier however
stated that this soultion does not give us any real gain. That is why
I decided to use standard name for hotplugged memory.
If you have a questions please drop me a line.
Daniel
Signed-off-by: Daniel Kiper <dkiper@xxxxxxxxxxxx>
---
arch/x86/Kconfig | 2 +-
drivers/xen/balloon.c | 95 ++++++++-------------------------------
include/linux/memory_hotplug.h | 3 +-
mm/memory_hotplug.c | 55 ++++++++++++++++-------
4 files changed, 61 insertions(+), 94 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index beb1aa7..9458685 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1273,7 +1273,7 @@ config ARCH_SELECT_MEMORY_MODEL
depends on ARCH_SPARSEMEM_ENABLE
config ARCH_MEMORY_PROBE
- def_bool X86_64 && !XEN
+ def_bool X86_64
depends on MEMORY_HOTPLUG
config ILLEGAL_POINTER_VALUE
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 31edc26..5120075 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -193,63 +193,11 @@ static void balloon_alarm(unsigned long unused)
}
#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
-static inline unsigned long current_target(void)
-{
- return balloon_stats.target_pages;
-}
-
static inline u64 is_memory_resource_reserved(void)
{
return balloon_stats.hotplug_start_paddr;
}
-/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-static int __ref xen_add_memory(int nid, u64 start, u64 size)
-{
- pg_data_t *pgdat = NULL;
- int new_pgdat = 0, ret;
-
- lock_system_sleep();
-
- if (!node_online(nid)) {
- pgdat = hotadd_new_pgdat(nid, start);
- ret = -ENOMEM;
- if (!pgdat)
- goto out;
- new_pgdat = 1;
- }
-
- /* call arch's memory hotadd */
- ret = arch_add_memory(nid, start, size);
-
- if (ret < 0)
- goto error;
-
- /* we online node here. we can't roll back from here. */
- node_set_online(nid);
-
- if (new_pgdat) {
- ret = register_one_node(nid);
- /*
- * If sysfs file of new node can't create, cpu on the node
- * can't be hot-added. There is no rollback way now.
- * So, check by BUG_ON() to catch it reluctantly..
- */
- BUG_ON(ret);
- }
-
- goto out;
-
-error:
- /* rollback pgdat allocation */
- if (new_pgdat)
- rollback_node_hotadd(nid, pgdat);
-
-out:
- unlock_system_sleep();
- return ret;
-}
-
static int allocate_additional_memory(unsigned long nr_pages)
{
long rc;
@@ -265,8 +213,6 @@ static int allocate_additional_memory(unsigned long
nr_pages)
if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list);
- spin_lock_irqsave(&balloon_lock, flags);
-
if (!is_memory_resource_reserved()) {
/*
@@ -280,7 +226,7 @@ static int allocate_additional_memory(unsigned long
nr_pages)
if (!r) {
rc = -ENOMEM;
- goto out;
+ goto out_0;
}
r->name = "System RAM";
@@ -293,12 +239,14 @@ static int allocate_additional_memory(unsigned long
nr_pages)
if (rc < 0) {
kfree(r);
- goto out;
+ goto out_0;
}
balloon_stats.hotplug_start_paddr = r->start;
}
+ spin_lock_irqsave(&balloon_lock, flags);
+
pfn = PFN_DOWN(balloon_stats.hotplug_start_paddr +
balloon_stats.hotplug_size);
for (i = 0; i < nr_pages; ++i, ++pfn)
@@ -310,7 +258,7 @@ static int allocate_additional_memory(unsigned long
nr_pages)
rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
if (rc < 0)
- goto out;
+ goto out_1;
pfn = PFN_DOWN(balloon_stats.hotplug_start_paddr +
balloon_stats.hotplug_size);
@@ -323,9 +271,10 @@ static int allocate_additional_memory(unsigned long
nr_pages)
balloon_stats.hotplug_size += rc << PAGE_SHIFT;
balloon_stats.current_pages += rc;
-out:
+out_1:
spin_unlock_irqrestore(&balloon_lock, flags);
+out_0:
return rc < 0 ? rc : rc != nr_pages;
}
@@ -337,11 +286,11 @@ static void hotplug_allocated_memory(void)
nid = memory_add_physaddr_to_nid(balloon_stats.hotplug_start_paddr);
- ret = xen_add_memory(nid, balloon_stats.hotplug_start_paddr,
+ ret = add_registered_memory(nid, balloon_stats.hotplug_start_paddr,
balloon_stats.hotplug_size);
if (ret) {
- pr_err("%s: xen_add_memory: Memory hotplug failed: %i\n",
+ pr_err("%s: add_registered_memory: Memory hotplug failed: %i\n",
__func__, ret);
goto error;
}
@@ -388,18 +337,6 @@ out:
balloon_stats.hotplug_size = 0;
}
#else
-static unsigned long current_target(void)
-{
- unsigned long target = balloon_stats.target_pages;
-
- target = min(target,
- balloon_stats.current_pages +
- balloon_stats.balloon_low +
- balloon_stats.balloon_high);
-
- return target;
-}
-
static inline u64 is_memory_resource_reserved(void)
{
return 0;
@@ -407,13 +344,21 @@ static inline u64 is_memory_resource_reserved(void)
static inline int allocate_additional_memory(unsigned long nr_pages)
{
+ /*
+ * CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is not set.
+ * balloon_stats.target_pages could not be bigger
+ * than balloon_stats.current_pages because additional
+ * memory allocation is not possible.
+ */
+ balloon_stats.target_pages = balloon_stats.current_pages;
+
return 0;
}
static inline void hotplug_allocated_memory(void)
{
}
-#endif
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
static int increase_reservation(unsigned long nr_pages)
{
@@ -553,7 +498,7 @@ static void balloon_process(struct work_struct *work)
mutex_lock(&balloon_mutex);
do {
- credit = current_target() - balloon_stats.current_pages;
+ credit = balloon_stats.target_pages -
balloon_stats.current_pages;
if (credit > 0) {
if (balloon_stats.balloon_low ||
balloon_stats.balloon_high)
@@ -572,7 +517,7 @@ static void balloon_process(struct work_struct *work)
} while ((credit != 0) && !need_sleep);
/* Schedule more work if there is some still to be done. */
- if (current_target() != balloon_stats.current_pages)
+ if (balloon_stats.target_pages != balloon_stats.current_pages)
mod_timer(&balloon_timer, jiffies + HZ);
else if (is_memory_resource_reserved())
hotplug_allocated_memory();
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 6652eae..37f1894 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -202,8 +202,7 @@ static inline int is_mem_section_removable(unsigned long
pfn,
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
-extern pg_data_t *hotadd_new_pgdat(int nid, u64 start);
-extern void rollback_node_hotadd(int nid, pg_data_t *pgdat);
+extern int add_registered_memory(int nid, u64 start, u64 size);
extern int add_memory(int nid, u64 start, u64 size);
extern int arch_add_memory(int nid, u64 start, u64 size);
extern int remove_memory(u64 start, u64 size);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 143e03c..48a65bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -453,7 +453,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
+static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
{
struct pglist_data *pgdat;
unsigned long zones_size[MAX_NR_ZONES] = {0};
@@ -473,32 +473,21 @@ pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
return pgdat;
}
-EXPORT_SYMBOL_GPL(hotadd_new_pgdat);
-void rollback_node_hotadd(int nid, pg_data_t *pgdat)
+static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
{
arch_refresh_nodedata(nid, NULL);
arch_free_nodedata(pgdat);
return;
}
-EXPORT_SYMBOL_GPL(rollback_node_hotadd);
-
/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-int __ref add_memory(int nid, u64 start, u64 size)
+static int __ref __add_memory(int nid, u64 start, u64 size)
{
pg_data_t *pgdat = NULL;
int new_pgdat = 0;
- struct resource *res;
int ret;
- lock_system_sleep();
-
- res = register_memory_resource(start, size);
- ret = -EEXIST;
- if (!res)
- goto out;
-
if (!node_online(nid)) {
pgdat = hotadd_new_pgdat(nid, start);
ret = -ENOMEM;
@@ -535,11 +524,45 @@ error:
/* rollback pgdat allocation and others */
if (new_pgdat)
rollback_node_hotadd(nid, pgdat);
- if (res)
- release_memory_resource(res);
out:
+ return ret;
+}
+
+int __ref add_registered_memory(int nid, u64 start, u64 size)
+{
+ int ret;
+
+ lock_system_sleep();
+ ret = __add_memory(nid, start, size);
unlock_system_sleep();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(add_registered_memory);
+
+int __ref add_memory(int nid, u64 start, u64 size)
+{
+ int ret = -EEXIST;
+ struct resource *res;
+
+ lock_system_sleep();
+
+ res = register_memory_resource(start, size);
+
+ if (!res)
+ goto out;
+
+ ret = __add_memory(nid, start, size);
+
+ if (!ret)
+ goto out;
+
+ release_memory_resource(res);
+
+out:
+ unlock_system_sleep();
+
return ret;
}
EXPORT_SYMBOL_GPL(add_memory);
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