On 2018-09-27 12:41, Juergen Gross wrote:
On 27/09/18 08:58, Arun KS wrote:
When free pages are done with higher order, time spend on
coalescing pages by buddy allocator can be reduced. With
section size of 256MB, hot add latency of a single section
shows improvement from 50-60 ms to less than 1 ms, hence
improving the hot add latency by 60%.
Modify external providers of online callback to align with
the change.
Signed-off-by: Arun KS <arunks@xxxxxxxxxxxxxx>
---
Changes since v2:
reuse code from __free_pages_boot_core()
Changes since v1:
- Removed prefetch()
Changes since RFC:
- Rebase.
- As suggested by Michal Hocko remove pages_per_block.
- Modifed external providers of online_page_callback.
v2: https://lore.kernel.org/patchwork/patch/991363/
v1: https://lore.kernel.org/patchwork/patch/989445/
RFC: https://lore.kernel.org/patchwork/patch/984754/
---
drivers/hv/hv_balloon.c | 6 ++++--
drivers/xen/balloon.c | 18 ++++++++++++++---
include/linux/memory_hotplug.h | 2 +-
mm/internal.h | 1 +
mm/memory_hotplug.c | 44
++++++++++++++++++++++++++++++------------
mm/page_alloc.c | 2 +-
6 files changed, 54 insertions(+), 19 deletions(-)
...
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index e12bb25..010cf4d 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -390,8 +390,8 @@ static enum bp_state
reserve_additional_memory(void)
/*
* add_memory_resource() will call online_pages() which in its turn
- * will call xen_online_page() callback causing deadlock if we don't
- * release balloon_mutex here. Unlocking here is safe because the
+ * will call xen_bring_pgs_online() callback causing deadlock if we
+ * don't release balloon_mutex here. Unlocking here is safe because
the
* callers drop the mutex before trying again.
*/
mutex_unlock(&balloon_mutex);
@@ -422,6 +422,18 @@ static void xen_online_page(struct page *page)
mutex_unlock(&balloon_mutex);
}
+static int xen_bring_pgs_online(struct page *pg, unsigned int order)
+{
+ unsigned long i, size = (1 << order);
+ unsigned long start_pfn = page_to_pfn(pg);
+
+ pr_debug("Online %lu pages starting at pfn 0x%lx\n", size,
start_pfn);
+ for (i = 0; i < size; i++)
+ xen_online_page(pfn_to_page(start_pfn + i));
Hi,
xen_online_page() isn't very complex and this is the only user.
Why don't you move its body in here and drop the extra function?
And now you can execute the loop with balloon_mutex held instead of
taking and releasing it in each iteration of the loop.
Point taken. Will incorporate them.
Regards,
Arun
Juergen
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