From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Apply the rmap chain lock batching to anon_vma_unlink() too.
This speeds up exit() on process chains with many processes,
when there is a lot of sharing.
Unfortunately this doesn't fix all lock contention -- file vmas
have a mapping lock that is also a problem. And even existing
anon_vmas still contend. But it's better than before.
Reviewed-by: Rik van Riel<riel@xxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
mm/rmap.c | 14 +++++++++-----
1 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index 4e93770..d4d3680 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -297,7 +297,9 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
return -ENOMEM;
}
-static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
+/* Caller must call anon_vma_unlock_batch */
+static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain,
+ struct anon_vma_lock_state *avs)
{
struct anon_vma *anon_vma = anon_vma_chain->anon_vma;
int empty;
@@ -306,12 +308,11 @@ static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
if (!anon_vma)
return;
- anon_vma_lock(anon_vma);
+ anon_vma_lock_batch(anon_vma, avs);
list_del(&anon_vma_chain->same_anon_vma);
/* We must garbage collect the anon_vma if it's empty */
empty = list_empty(&anon_vma->head);
- anon_vma_unlock(anon_vma);
if (empty)
put_anon_vma(anon_vma);
@@ -320,16 +321,19 @@ static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
void unlink_anon_vmas(struct vm_area_struct *vma)
{
struct anon_vma_chain *avc, *next;
-
+ struct anon_vma_lock_state avs;
+
/*
* Unlink each anon_vma chained to the VMA. This list is ordered
* from newest to oldest, ensuring the root anon_vma gets freed last.
*/
+ anon_vma_lock_batch_init(&avs);
list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
- anon_vma_unlink(avc);
+ anon_vma_unlink(avc, &avs);
list_del(&avc->same_vma);
anon_vma_chain_free(avc);
}
+ anon_vma_unlock_batch(&avs);
}
static void anon_vma_ctor(void *data)
--
1.7.4.4
--
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