From 8b312bb9a795c9c07661aee7b694cbfd3217e25c Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Fri, 13 Dec 2013 19:26:21 -0800 Subject: [PATCH] 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 Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ion/ion_heap.c | 36 +++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c index 0a5cea0..ce31561 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; } -- 2.7.4