mm/gup_benchmark.c

   1 #include <linux/kernel.h>
   2 #include <linux/mm.h>
   3 #include <linux/slab.h>
   4 #include <linux/uaccess.h>
   5 #include <linux/ktime.h>
   6 #include <linux/debugfs.h>
   7
   8 #define GUP_FAST_BENCHMARK      _IOWR('g', 1, struct gup_benchmark)
   9
  10 struct gup_benchmark {
  11         __u64 delta_usec;
  12         __u64 addr;
  13         __u64 size;
  14         __u32 nr_pages_per_call;
  15         __u32 flags;
  16 };
  17
  18 static int __gup_benchmark_ioctl(unsigned int cmd,
  19                 struct gup_benchmark *gup)
  20 {
  21         ktime_t start_time, end_time;
  22         unsigned long i, nr, nr_pages, addr, next;
  23         struct page **pages;
  24
  25         nr_pages = gup->size / PAGE_SIZE;
  26         pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
  27         if (!pages)
  28                 return -ENOMEM;
  29
  30         i = 0;
  31         nr = gup->nr_pages_per_call;
  32         start_time = ktime_get();
  33         for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
  34                 if (nr != gup->nr_pages_per_call)
  35                         break;
  36
  37                 next = addr + nr * PAGE_SIZE;
  38                 if (next > gup->addr + gup->size) {
  39                         next = gup->addr + gup->size;
  40                         nr = (next - addr) / PAGE_SIZE;
  41                 }
  42
  43                 nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
  44                 if (nr <= 0)
  45                         break;
  46                 i += nr;
  47         }
  48         end_time = ktime_get();
  49
  50         gup->delta_usec = ktime_us_delta(end_time, start_time);
  51         gup->size = addr - gup->addr;
  52
  53         for (i = 0; i < nr_pages; i++) {
  54                 if (!pages[i])
  55                         break;
  56                 put_page(pages[i]);
  57         }
  58
  59         kvfree(pages);
  60         return 0;
  61 }
  62
  63 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  64                 unsigned long arg)
  65 {
  66         struct gup_benchmark gup;
  67         int ret;
  68
  69         if (cmd != GUP_FAST_BENCHMARK)
  70                 return -EINVAL;
  71
  72         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
  73                 return -EFAULT;
  74
  75         ret = __gup_benchmark_ioctl(cmd, &gup);
  76         if (ret)
  77                 return ret;
  78
  79         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
  80                 return -EFAULT;
  81
  82         return 0;
  83 }
  84
  85 static const struct file_operations gup_benchmark_fops = {
  86         .open = nonseekable_open,
  87         .unlocked_ioctl = gup_benchmark_ioctl,
  88 };
  89
  90 static int gup_benchmark_init(void)
  91 {
  92         void *ret;
  93
  94         ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
  95                         &gup_benchmark_fops);
  96         if (!ret)
  97                 pr_warn("Failed to create gup_benchmark in debugfs");
  98
  99         return 0;
 100 }
 101
 102 late_initcall(gup_benchmark_init);