diff options
author | Colin Cross <ccross@android.com> | 2013-12-13 19:26:21 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-14 08:59:53 -0800 |
commit | 8b312bb9a795c9c07661aee7b694cbfd3217e25c (patch) | |
tree | 1d4234db865517dd77fb3e5f30323887c973207d /drivers/staging/android/ion/ion_heap.c | |
parent | f0f06763820e5b5f6e13afa814e68e8f4d955c45 (diff) |
ion: optimize ion_heap_buffer_zero
ion_heap_buffer_zero can spend a long time in unmap_kernel_range
if it has to broadcast a tlb flush to every cpu for every page.
Modify it to batch pages into a larger region to clear using a
single mapping. This may cause the mapping size to change if
the buffer size is not a multiple of the mapping size, so
switch to allocating the address space for each chunk. This
allows us to use vm_map_ram to handle the allocation and mapping
together.
The number of pages to zero using a single mapping is set to 32
to hit the fastpath in vm_map_ram.
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/android/ion/ion_heap.c')
-rw-r--r-- | drivers/staging/android/ion/ion_heap.c | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c index 0a5cea0c01e3..ce3156163704 100644 --- a/drivers/staging/android/ion/ion_heap.c +++ b/drivers/staging/android/ion/ion_heap.c @@ -100,40 +100,48 @@ int ion_heap_map_user(struct ion_heap *heap, struct ion_buffer *buffer, return 0; } +static int ion_heap_clear_pages(struct page **pages, int num, pgprot_t pgprot) +{ + void *addr = vm_map_ram(pages, num, -1, pgprot); + if (!addr) + return -ENOMEM; + memset(addr, 0, PAGE_SIZE * num); + vm_unmap_ram(addr, num); + + return 0; +} + int ion_heap_buffer_zero(struct ion_buffer *buffer) { struct sg_table *table = buffer->sg_table; pgprot_t pgprot; struct scatterlist *sg; - struct vm_struct *vm_struct; int i, j, ret = 0; + struct page *pages[32]; + int k = 0; if (buffer->flags & ION_FLAG_CACHED) pgprot = PAGE_KERNEL; else pgprot = pgprot_writecombine(PAGE_KERNEL); - vm_struct = get_vm_area(PAGE_SIZE, VM_ALLOC); - if (!vm_struct) - return -ENOMEM; - for_each_sg(table->sgl, sg, table->nents, i) { struct page *page = sg_page(sg); unsigned long len = sg->length; for (j = 0; j < len / PAGE_SIZE; j++) { - struct page *sub_page = page + j; - struct page **pages = &sub_page; - ret = map_vm_area(vm_struct, pgprot, &pages); - if (ret) - goto end; - memset(vm_struct->addr, 0, PAGE_SIZE); - unmap_kernel_range((unsigned long)vm_struct->addr, - PAGE_SIZE); + pages[k++] = page + j; + if (k == ARRAY_SIZE(pages)) { + ret = ion_heap_clear_pages(pages, k, pgprot); + if (ret) + goto end; + k = 0; + } } + if (k) + ret = ion_heap_clear_pages(pages, k, pgprot); } end: - free_vm_area(vm_struct); return ret; } |