Subject: + mmvmacache-optimize-overflow-system-wide-flushing.patch added to -mm tree
To: davidlohr@xxxxxx,aswin@xxxxxx,oleg@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 15 Apr 2014 13:52:21 -0700
The patch titled
Subject: mm,vmacache: optimize overflow system-wide flushing
has been added to the -mm tree. Its filename is
mmvmacache-optimize-overflow-system-wide-flushing.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmvmacache-optimize-overflow-system-wide-flushing.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmvmacache-optimize-overflow-system-wide-flushing.patch
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From: Davidlohr Bueso <davidlohr@xxxxxx>
Subject: mm,vmacache: optimize overflow system-wide flushing
For single threaded workloads, we can avoid flushing and iterating through
the entire list of tasks, making the whole function a lot faster,
requiring only a single atomic read for the mm_users.
Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Aswin Chandramouleeswaran <aswin@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmacache.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff -puN mm/vmacache.c~mmvmacache-optimize-overflow-system-wide-flushing mm/vmacache.c
--- a/mm/vmacache.c~mmvmacache-optimize-overflow-system-wide-flushing
+++ a/mm/vmacache.c
@@ -17,6 +17,16 @@ void vmacache_flush_all(struct mm_struct
{
struct task_struct *g, *p;
+ /*
+ * Single threaded tasks need not iterate the entire
+ * list of process. We can avoid the flushing as well
+ * since the mm's seqnum was increased and don't have
+ * to worry about other threads' seqnum. Current's
+ * flush will occur upon the next lookup.
+ */
+ if (atomic_read(&mm->mm_users) == 1)
+ return;
+
rcu_read_lock();
for_each_process_thread(g, p) {
/*
_
Patches currently in -mm which might be from davidlohr@xxxxxx are
mm-fix-config_debug_vm_rb-description.patch
mmvmacache-add-debug-data.patch
mmvmacache-optimize-overflow-system-wide-flushing.patch
ipc-constify-ipc_ops.patch
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