VM_IOREMAP is used to access hardware through a mechanism called
I/O mapped memory. Android binder is a IPC machanism which will
not access I/O memory.
Also VM_IOREMAP has alignment requiement which may not needed in
binder.
__get_vm_area_node()
{
...
if (flags & VM_IOREMAP)
align = 1ul << clamp_t(int, fls_long(size),
PAGE_SHIFT, IOREMAP_MAX_ORDER);
...
}
This patch use VM_ALLOC to get vm area.
Below is the throughput test result:
# ./binderThroughputTest -w 100
I run this command 10 times:
before after
average iterations per sec: 11199.9 11886.9
No performance regression found throgh binder test.
Signed-off-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
---
drivers/android/binder.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 3c71b98..b5908ec 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2901,7 +2901,7 @@ static int binder_mmap(struct file *filp, struct vm_area_struct *vma)
goto err_already_mapped;
}
- area = get_vm_area(vma->vm_end - vma->vm_start, VM_IOREMAP);
+ area = get_vm_area(vma->vm_end - vma->vm_start, VM_ALLOC);
if (area == NULL) {
ret = -ENOMEM;
failure_string = "get_vm_area";
--
1.9.1
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