The patch titled
slob: remove bigblock tracking
has been added to the -mm tree. Its filename is
slob-remove-bigblock-tracking.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: slob: remove bigblock tracking
From: Nick Piggin <npiggin@xxxxxxx>
Remove the bigblock lists in favour of using compound pages and going directly
to the page allocator. Allocation size is stored in page->private, which also
makes ksize more accurate than it previously was.
Saves ~.5K of code, and 12-24 bytes overhead per >= PAGE_SIZE allocation.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Acked-by: Matt Mackall <mpm@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slob.c | 101 ++++++++++++++--------------------------------------
1 files changed, 28 insertions(+), 73 deletions(-)
diff -puN mm/slob.c~slob-remove-bigblock-tracking mm/slob.c
--- a/mm/slob.c~slob-remove-bigblock-tracking
+++ a/mm/slob.c
@@ -18,9 +18,11 @@
* Above this is an implementation of kmalloc/kfree. Blocks returned
* from kmalloc are 4-byte aligned and prepended with a 4-byte header.
* If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
- * __get_free_pages directly so that it can return page-aligned blocks
- * and keeps a linked list of such pages and their orders. These
- * objects are detected in kfree() by their page alignment.
+ * __get_free_pages directly, allocating compound pages so the page order
+ * does not have to be separately tracked, and also stores the exact
+ * allocation size in page->private so that it can be used to accurately
+ * provide ksize(). These objects are detected in kfree() because slob_page()
+ * is false for them.
*
* SLAB is emulated on top of SLOB by simply calling constructors and
* destructors for every SLAB allocation. Objects are returned with the
@@ -29,7 +31,8 @@
* alignment. Again, objects of page-size or greater are allocated by
* calling __get_free_pages. As SLAB objects know their size, no separate
* size bookkeeping is necessary and there is essentially no allocation
- * space overhead.
+ * space overhead, and compound pages aren't needed for multi-page
+ * allocations.
*/
#include <linux/kernel.h>
@@ -381,48 +384,26 @@ out:
* End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend.
*/
-struct bigblock {
- int order;
- void *pages;
- struct bigblock *next;
-};
-typedef struct bigblock bigblock_t;
-
-static bigblock_t *bigblocks;
-
-static DEFINE_SPINLOCK(block_lock);
-
-
void *__kmalloc(size_t size, gfp_t gfp)
{
- slob_t *m;
- bigblock_t *bb;
- unsigned long flags;
-
if (size < PAGE_SIZE - SLOB_UNIT) {
+ slob_t *m;
m = slob_alloc(size + SLOB_UNIT, gfp, 0);
if (m)
m->units = size;
return m+1;
- }
-
- bb = slob_alloc(sizeof(bigblock_t), gfp, 0);
- if (!bb)
- return 0;
-
- bb->order = get_order(size);
- bb->pages = (void *)__get_free_pages(gfp, bb->order);
+ } else {
+ void *ret;
- if (bb->pages) {
- spin_lock_irqsave(&block_lock, flags);
- bb->next = bigblocks;
- bigblocks = bb;
- spin_unlock_irqrestore(&block_lock, flags);
- return bb->pages;
+ ret = (void *) __get_free_pages(gfp | __GFP_COMP,
+ get_order(size));
+ if (ret) {
+ struct page *page;
+ page = virt_to_page(ret);
+ page->private = size;
+ }
+ return ret;
}
-
- slob_free(bb, sizeof(bigblock_t));
- return 0;
}
EXPORT_SYMBOL(__kmalloc);
@@ -462,59 +443,33 @@ EXPORT_SYMBOL(krealloc);
void kfree(const void *block)
{
struct slob_page *sp;
- slob_t *m;
- bigblock_t *bb, **last = &bigblocks;
- unsigned long flags;
if (!block)
return;
sp = (struct slob_page *)virt_to_page(block);
- if (!slob_page(sp)) {
- /* on the big block list */
- spin_lock_irqsave(&block_lock, flags);
- for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) {
- if (bb->pages == block) {
- *last = bb->next;
- spin_unlock_irqrestore(&block_lock, flags);
- free_pages((unsigned long)block, bb->order);
- slob_free(bb, sizeof(bigblock_t));
- return;
- }
- }
- spin_unlock_irqrestore(&block_lock, flags);
- WARN_ON(1);
- return;
- }
-
- m = (slob_t *)block - 1;
- slob_free(m, m->units + SLOB_UNIT);
- return;
+ if (slob_page(sp)) {
+ slob_t *m = (slob_t *)block - 1;
+ slob_free(m, m->units + SLOB_UNIT);
+ } else
+ put_page(&sp->page);
}
EXPORT_SYMBOL(kfree);
+/* can't use ksize for kmem_cache_alloc memory, only kmalloc */
size_t ksize(const void *block)
{
struct slob_page *sp;
- bigblock_t *bb;
- unsigned long flags;
if (!block)
return 0;
sp = (struct slob_page *)virt_to_page(block);
- if (!slob_page(sp)) {
- spin_lock_irqsave(&block_lock, flags);
- for (bb = bigblocks; bb; bb = bb->next)
- if (bb->pages == block) {
- spin_unlock_irqrestore(&slob_lock, flags);
- return PAGE_SIZE << bb->order;
- }
- spin_unlock_irqrestore(&block_lock, flags);
- }
-
- return ((slob_t *)block - 1)->units + SLOB_UNIT;
+ if (slob_page(sp))
+ return ((slob_t *)block - 1)->units + SLOB_UNIT;
+ else
+ return sp->page.private;
}
struct kmem_cache {
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
mm-fix-fault-vs-invalidate-race-for-linear-mappings.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear.patch
mm-merge-nopfn-into-fault.patch
mm-remove-legacy-cruft.patch
mm-debug-check-for-the-fault-vs-invalidate-race.patch
mm-fix-clear_page_dirty_for_io-vs-fault-race.patch
slob-rework-freelist-handling.patch
slob-remove-bigblock-tracking.patch
slob-improved-alignment-handling.patch
mm-document-fault_data-and-flags.patch
fs-introduce-some-page-buffer-invariants.patch
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