The patch titled
SLUB: rework slab order determination
has been added to the -mm tree. Its filename is
slub-rework-slab-order-determination.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: SLUB: rework slab order determination
From: Christoph Lameter <clameter@xxxxxxx>
In some cases SLUB is creating uselessly slabs that are larger than
slub_max_order. Also the layout of some of the slabs was not satisfactory.
Go to an iterarive approach.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 66 ++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 52 insertions(+), 14 deletions(-)
diff -puN mm/slub.c~slub-rework-slab-order-determination mm/slub.c
--- a/mm/slub.c~slub-rework-slab-order-determination
+++ a/mm/slub.c
@@ -1572,37 +1572,75 @@ static int slub_nomerge;
* requested a higher mininum order then we start with that one instead of
* the smallest order which will fit the object.
*/
-static int calculate_order(int size)
+static inline int slab_order(int size, int min_objects,
+ int max_order, int fract_leftover)
{
int order;
int rem;
- for (order = max(slub_min_order, fls(size - 1) - PAGE_SHIFT);
- order < MAX_ORDER; order++) {
- unsigned long slab_size = PAGE_SIZE << order;
+ for (order = max(slub_min_order,
+ fls(min_objects * size - 1) - PAGE_SHIFT);
+ order <= max_order; order++) {
- if (order < slub_max_order &&
- slab_size < slub_min_objects * size)
- continue;
+ unsigned long slab_size = PAGE_SIZE << order;
- if (slab_size < size)
+ if (slab_size < min_objects * size)
continue;
- if (order >= slub_max_order)
- break;
-
rem = slab_size % size;
- if (rem <= slab_size / 8)
+ if (rem <= slab_size / fract_leftover)
break;
}
- if (order >= MAX_ORDER)
- return -E2BIG;
return order;
}
+static inline int calculate_order(int size)
+{
+ int order;
+ int min_objects;
+ int fraction;
+
+ /*
+ * Attempt to find best configuration for a slab. This
+ * works by first attempting to generate a layout with
+ * the best configuration and backing off gradually.
+ *
+ * First we reduce the acceptable waste in a slab. Then
+ * we reduce the minimum objects required in a slab.
+ */
+ min_objects = slub_min_objects;
+ while (min_objects > 1) {
+ fraction = 8;
+ while (fraction >= 4) {
+ order = slab_order(size, min_objects,
+ slub_max_order, fraction);
+ if (order <= slub_max_order)
+ return order;
+ fraction /= 2;
+ }
+ min_objects /= 2;
+ }
+
+ /*
+ * We were unable to place multiple objects in a slab. Now
+ * lets see if we can place a single object there.
+ */
+ order = slab_order(size, 1, slub_max_order, 1);
+ if (order <= slub_max_order)
+ return order;
+
+ /*
+ * Doh this slab cannot be placed using slub_max_order.
+ */
+ order = slab_order(size, 1, MAX_ORDER, 1);
+ if (order <= MAX_ORDER)
+ return order;
+ return -ENOSYS;
+}
+
/*
* Figure out what the alignment of the objects will be.
*/
_
Patches currently in -mm which might be from clameter@xxxxxxx are
origin.patch
slub-add-support-for-dynamic-cacheline-size-determination.patch
slub-add-support-for-dynamic-cacheline-size-determination-fix.patch
slub-after-object-padding-only-needed-for-redzoning.patch
slub-slabinfo-upgrade.patch
slub-use-check_valid_pointer-in-kmem_ptr_validate.patch
slub-clean-up-krealloc.patch
slub-clean-up-krealloc-fix.patch
slub-get-rid-of-finish_bootstrap.patch
slub-update-comments.patch
slub-add-macros-for-scanning-objects-in-a-slab.patch
slub-move-resiliency-check-into-sysfs-section.patch
slub-introduce-debugslabpage.patch
slub-consolidate-trace-code.patch
slub-move-tracking-definitions-and-check_valid_pointer-away-from-debug-code.patch
slub-add-config_slub_debug.patch
slub-include-lifetime-stats-and-sets-of-cpus--nodes-in-tracking-output.patch
slub-include-lifetime-stats-and-sets-of-cpus--nodes-in-tracking-output-fix.patch
slub-rework-slab-order-determination.patch
quicklist-support-for-ia64.patch
quicklist-support-for-x86_64.patch
slub-exploit-page-mobility-to-increase-allocation-order.patch
slub-mm-only-make-slub-the-default-slab-allocator.patch
slub-reduce-antifrag-max-order.patch
slub-i386-support.patch
remove-constructor-from-buffer_head.patch
slab-shutdown-cache_reaper-when-cpu-goes-down.patch
mm-implement-swap-prefetching.patch
revoke-core-code-slab-allocators-remove-slab_debug_initial-flag-revoke.patch
vmstat-use-our-own-timer-events.patch
vmstat-use-our-own-timer-events-fix.patch
make-vm-statistics-update-interval-configurable.patch
make-vm-statistics-update-interval-configurable-fix.patch
move-remote-node-draining-out-of-slab-allocators.patch
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