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Date: Fri, 22 Aug 2014 12:53:10 -0400
From: Tejun Heo <tj@...nel.org>
To: akpm@...ux-foundation.org, cl@...ux-foundation.org
Cc: laijs@...fujitsu.com, linux-kernel@...r.kernel.org,
vgoyal@...hat.com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 06/15] percpu: move region iterations out of pcpu_[de]populate_chunk()
Previously, pcpu_[de]populate_chunk() were called with the range which
may contain multiple target regions in it and
pcpu_[de]populate_chunk() iterated over the regions. This has the
benefit of batching up cache flushes for all the regions; however,
we're planning to add more bookkeeping logic around [de]population to
support atomic allocations and this delegation of iterations gets in
the way.
This patch moves the region iterations out of
pcpu_[de]populate_chunk() into its callers - pcpu_alloc() and
pcpu_reclaim() - so that we can later add logic to track more states
around them. This change may make cache and tlb flushes more frequent
but multi-region [de]populations are rare anyway and if this actually
becomes a problem, it's not difficult to factor out cache flushes as
separate callbacks which are directly invoked from percpu.c.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
mm/percpu-km.c | 6 ++++--
mm/percpu-vm.c | 57 ++++++++++++++++-----------------------------------------
mm/percpu.c | 19 ++++++++-----------
3 files changed, 28 insertions(+), 54 deletions(-)
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index 9a9096f..a6e34bc 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -33,12 +33,14 @@
#include <linux/log2.h>
-static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
+static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
+ int page_start, int page_end)
{
return 0;
}
-static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
+static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
+ int page_start, int page_end)
{
/* nada */
}
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index edf7097..538998a 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -261,8 +261,8 @@ static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
/**
* pcpu_populate_chunk - populate and map an area of a pcpu_chunk
* @chunk: chunk of interest
- * @off: offset to the area to populate
- * @size: size of the area to populate in bytes
+ * @page_start: the start page
+ * @page_end: the end page
*
* For each cpu, populate and map pages [@page_start,@page_end) into
* @chunk.
@@ -270,66 +270,43 @@ static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
* CONTEXT:
* pcpu_alloc_mutex, does GFP_KERNEL allocation.
*/
-static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
+static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
+ int page_start, int page_end)
{
- int page_start = PFN_DOWN(off);
- int page_end = PFN_UP(off + size);
- int free_end = page_start, unmap_end = page_start;
struct page **pages;
- int rs, re, rc;
pages = pcpu_get_pages(chunk);
if (!pages)
return -ENOMEM;
- /* alloc and map */
- pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
- rc = pcpu_alloc_pages(chunk, pages, rs, re);
- if (rc)
- goto err_free;
- free_end = re;
- }
+ if (pcpu_alloc_pages(chunk, pages, page_start, page_end))
+ return -ENOMEM;
- pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
- rc = pcpu_map_pages(chunk, pages, rs, re);
- if (rc)
- goto err_unmap;
- unmap_end = re;
+ if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
+ pcpu_free_pages(chunk, pages, page_start, page_end);
+ return -ENOMEM;
}
pcpu_post_map_flush(chunk, page_start, page_end);
return 0;
-
-err_unmap:
- pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
- pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
- pcpu_unmap_pages(chunk, pages, rs, re);
- pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
-err_free:
- pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
- pcpu_free_pages(chunk, pages, rs, re);
- return rc;
}
/**
* pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
* @chunk: chunk to depopulate
- * @off: offset to the area to depopulate
- * @size: size of the area to depopulate in bytes
+ * @page_start: the start page
+ * @page_end: the end page
*
* For each cpu, depopulate and unmap pages [@page_start,@page_end)
- * from @chunk. If @flush is true, vcache is flushed before unmapping
- * and tlb after.
+ * from @chunk.
*
* CONTEXT:
* pcpu_alloc_mutex.
*/
-static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
+static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
+ int page_start, int page_end)
{
- int page_start = PFN_DOWN(off);
- int page_end = PFN_UP(off + size);
struct page **pages;
- int rs, re;
/*
* If control reaches here, there must have been at least one
@@ -342,13 +319,11 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
/* unmap and free */
pcpu_pre_unmap_flush(chunk, page_start, page_end);
- pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
- pcpu_unmap_pages(chunk, pages, rs, re);
+ pcpu_unmap_pages(chunk, pages, page_start, page_end);
/* no need to flush tlb, vmalloc will handle it lazily */
- pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
- pcpu_free_pages(chunk, pages, rs, re);
+ pcpu_free_pages(chunk, pages, page_start, page_end);
}
static struct pcpu_chunk *pcpu_create_chunk(void)
diff --git a/mm/percpu.c b/mm/percpu.c
index 12b0049..c8fe482 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -807,20 +807,17 @@ area_found:
page_start = PFN_DOWN(off);
page_end = PFN_UP(off + size);
- rs = page_start;
- pcpu_next_pop(chunk, &rs, &re, page_end);
-
- if (rs != page_start || re != page_end) {
+ pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
WARN_ON(chunk->immutable);
- if (pcpu_populate_chunk(chunk, off, size)) {
+ if (pcpu_populate_chunk(chunk, rs, re)) {
spin_lock_irqsave(&pcpu_lock, flags);
pcpu_free_area(chunk, off);
err = "failed to populate";
goto fail_unlock;
}
- bitmap_set(chunk->populated, page_start, page_end - page_start);
+ bitmap_set(chunk->populated, rs, re - rs);
}
mutex_unlock(&pcpu_alloc_mutex);
@@ -919,12 +916,12 @@ static void pcpu_reclaim(struct work_struct *work)
spin_unlock_irq(&pcpu_lock);
list_for_each_entry_safe(chunk, next, &todo, list) {
- int rs = 0, re;
-
- pcpu_next_unpop(chunk, &rs, &re, PFN_UP(pcpu_unit_size));
- if (rs || re != PFN_UP(pcpu_unit_size))
- pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size);
+ int rs, re;
+ pcpu_for_each_pop_region(chunk, rs, re, 0, pcpu_unit_pages) {
+ pcpu_depopulate_chunk(chunk, rs, re);
+ bitmap_clear(chunk->populated, rs, re - rs);
+ }
pcpu_destroy_chunk(chunk);
}
--
1.9.3
--
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