The patch titled
memcg: coalesce uncharge at unmap and truncation
has been added to the -mm tree. Its filename is
memcg-coalesce-uncharge-at-unmap-and-truncation.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg: coalesce uncharge at unmap and truncation
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
In massive parallel enviroment, res_counter can be a performance
bottleneck. One strong techinque to reduce lock contention is reducing
calls by coalescing some amount of calls into one.
Considering charge/uncharge chatacteristic,
- charge is done one by one via demand-paging.
- uncharge is done by
- in chunk at munmap, truncate, exit, execve...
- one by one via vmscan/paging.
It seems we have a chance in uncharge at unmap/truncation.
This patch is a for coalescing uncharge. For avoiding scattering memcg's
structure to functions under /mm, this patch adds memcg batch uncharge
information to the task.
The degree of coalescing depends on callers
- at invalidate/trucate... pagevec size
- at unmap ....ZAP_BLOCK_SIZE
(memory itself will be freed in this degree.)
Then, we'll not coalescing too much.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN include/linux/memcontrol.h~memcg-coalesce-uncharge-at-unmap-and-truncation include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~memcg-coalesce-uncharge-at-unmap-and-truncation
+++ a/include/linux/memcontrol.h
@@ -54,6 +54,11 @@ extern void mem_cgroup_rotate_lru_list(s
extern void mem_cgroup_del_lru(struct page *page);
extern void mem_cgroup_move_lists(struct page *page,
enum lru_list from, enum lru_list to);
+
+/* For coalescing uncharge for reducing memcg' overhead*/
+extern void mem_cgroup_uncharge_start(void);
+extern void mem_cgroup_uncharge_end(void);
+
extern void mem_cgroup_uncharge_page(struct page *page);
extern void mem_cgroup_uncharge_cache_page(struct page *page);
extern int mem_cgroup_shmem_charge_fallback(struct page *page,
@@ -151,6 +156,14 @@ static inline void mem_cgroup_cancel_cha
{
}
+static inline void mem_cgroup_uncharge_start(void)
+{
+}
+
+static inline void mem_cgroup_uncharge_end(void)
+{
+}
+
static inline void mem_cgroup_uncharge_page(struct page *page)
{
}
diff -puN include/linux/sched.h~memcg-coalesce-uncharge-at-unmap-and-truncation include/linux/sched.h
--- a/include/linux/sched.h~memcg-coalesce-uncharge-at-unmap-and-truncation
+++ a/include/linux/sched.h
@@ -1543,6 +1543,13 @@ struct task_struct {
unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
unsigned long stack_start;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */
+ struct memcg_batch_info {
+ int do_batch;
+ struct mem_cgroup *memcg;
+ long pages, memsw;
+ } memcg_batch;
+#endif
};
/* Future-safe accessor for struct task_struct's cpus_allowed. */
diff -puN mm/memcontrol.c~memcg-coalesce-uncharge-at-unmap-and-truncation mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-coalesce-uncharge-at-unmap-and-truncation
+++ a/mm/memcontrol.c
@@ -1826,6 +1826,49 @@ void mem_cgroup_cancel_charge_swapin(str
css_put(&mem->css);
}
+static void
+__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype)
+{
+ struct memcg_batch_info *batch = NULL;
+ bool uncharge_memsw = true;
+ /* If swapout, usage of swap doesn't decrease */
+ if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
+ uncharge_memsw = false;
+ /*
+ * do_batch > 0 when unmapping pages or inode invalidate/truncate.
+ * In those cases, all pages freed continously can be expected to be in
+ * the same cgroup and we have chance to coalesce uncharges.
+ * And, we do uncharge one by one if this is killed by OOM.
+ */
+ if (!current->memcg_batch.do_batch || test_thread_flag(TIF_MEMDIE))
+ goto direct_uncharge;
+
+ batch = ¤t->memcg_batch;
+ /*
+ * In usual, we do css_get() when we remember memcg pointer.
+ * But in this case, we keep res->usage until end of a series of
+ * uncharges. Then, it's ok to ignore memcg's refcnt.
+ */
+ if (!batch->memcg)
+ batch->memcg = mem;
+ /*
+ * In typical case, batch->memcg == mem. This means we can
+ * merge a series of uncharges to an uncharge of res_counter.
+ * If not, we uncharge res_counter ony by one.
+ */
+ if (batch->memcg != mem)
+ goto direct_uncharge;
+ /* remember freed charge and uncharge it later */
+ batch->pages += PAGE_SIZE;
+ if (uncharge_memsw)
+ batch->memsw += PAGE_SIZE;
+ return;
+direct_uncharge:
+ res_counter_uncharge(&mem->res, PAGE_SIZE);
+ if (uncharge_memsw)
+ res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+ return;
+}
/*
* uncharge if !page_mapped(page)
@@ -1874,12 +1917,8 @@ __mem_cgroup_uncharge_common(struct page
break;
}
- if (!mem_cgroup_is_root(mem)) {
- res_counter_uncharge(&mem->res, PAGE_SIZE);
- if (do_swap_account &&
- (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
- res_counter_uncharge(&mem->memsw, PAGE_SIZE);
- }
+ if (!mem_cgroup_is_root(mem))
+ __do_uncharge(mem, ctype);
if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
mem_cgroup_swap_statistics(mem, true);
mem_cgroup_charge_statistics(mem, pc, false);
@@ -1925,6 +1964,46 @@ void mem_cgroup_uncharge_cache_page(stru
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
}
+/*
+ * batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
+ * In that cases, pages are freed continuously and we can expect pages
+ * are in the same memcg. All these calls itself limits the number of
+ * pages freed at once, then uncharge_start/end() is called properly.
+ */
+
+void mem_cgroup_uncharge_start(void)
+{
+ if (!current->memcg_batch.do_batch) {
+ current->memcg_batch.memcg = NULL;
+ current->memcg_batch.pages = 0;
+ current->memcg_batch.memsw = 0;
+ }
+ current->memcg_batch.do_batch++;
+}
+
+void mem_cgroup_uncharge_end(void)
+{
+ struct mem_cgroup *mem;
+
+ if (!current->memcg_batch.do_batch)
+ return;
+
+ current->memcg_batch.do_batch--;
+ if (current->memcg_batch.do_batch) /* Nested ? */
+ return;
+
+ mem = current->memcg_batch.memcg;
+ if (!mem)
+ return;
+ /* This "mem" is valid bacause we hide charges behind us. */
+ if (current->memcg_batch.pages)
+ res_counter_uncharge(&mem->res, current->memcg_batch.pages);
+ if (current->memcg_batch.memsw)
+ res_counter_uncharge(&mem->memsw, current->memcg_batch.memsw);
+ /* Not necessary. but forget this pointer */
+ current->memcg_batch.memcg = NULL;
+}
+
#ifdef CONFIG_SWAP
/*
* called after __delete_from_swap_cache() and drop "page" account.
diff -puN mm/memory.c~memcg-coalesce-uncharge-at-unmap-and-truncation mm/memory.c
--- a/mm/memory.c~memcg-coalesce-uncharge-at-unmap-and-truncation
+++ a/mm/memory.c
@@ -940,6 +940,7 @@ static unsigned long unmap_page_range(st
details = NULL;
BUG_ON(addr >= end);
+ mem_cgroup_uncharge_start();
tlb_start_vma(tlb, vma);
pgd = pgd_offset(vma->vm_mm, addr);
do {
@@ -952,6 +953,7 @@ static unsigned long unmap_page_range(st
zap_work, details);
} while (pgd++, addr = next, (addr != end && *zap_work > 0));
tlb_end_vma(tlb, vma);
+ mem_cgroup_uncharge_end();
return addr;
}
diff -puN mm/truncate.c~memcg-coalesce-uncharge-at-unmap-and-truncation mm/truncate.c
--- a/mm/truncate.c~memcg-coalesce-uncharge-at-unmap-and-truncation
+++ a/mm/truncate.c
@@ -272,6 +272,7 @@ void truncate_inode_pages_range(struct a
pagevec_release(&pvec);
break;
}
+ mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
@@ -286,6 +287,7 @@ void truncate_inode_pages_range(struct a
unlock_page(page);
}
pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
}
}
EXPORT_SYMBOL(truncate_inode_pages_range);
@@ -327,6 +329,7 @@ unsigned long invalidate_mapping_pages(s
pagevec_init(&pvec, 0);
while (next <= end &&
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t index;
@@ -354,6 +357,7 @@ unsigned long invalidate_mapping_pages(s
break;
}
pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
cond_resched();
}
return ret;
@@ -428,6 +432,7 @@ int invalidate_inode_pages2_range(struct
while (next <= end && !wrapped &&
pagevec_lookup(&pvec, mapping, next,
min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
+ mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index;
@@ -477,6 +482,7 @@ int invalidate_inode_pages2_range(struct
unlock_page(page);
}
pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
cond_resched();
}
return ret;
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
mm-add-notifier-in-pageblock-isolation-for-balloon-drivers.patch
powerpc-make-the-cmm-memory-hotplug-aware.patch
memcg-coalesce-uncharge-at-unmap-and-truncation.patch
memcg-coalesce-charges-per-cpu.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
