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 #define GUP_LONGTERM_BENCHMARK  _IOWR('g', 2, struct gup_benchmark)
  10 #define GUP_BENCHMARK           _IOWR('g', 3, struct gup_benchmark)
  11
  12 struct gup_benchmark {
  13         __u64 get_delta_usec;
  14         __u64 put_delta_usec;
  15         __u64 addr;
  16         __u64 size;
  17         __u32 nr_pages_per_call;
  18         __u32 flags;
  19         __u64 expansion[10];    /* For future use */
  20 };
  21
  22 static int __gup_benchmark_ioctl(unsigned int cmd,
  23                 struct gup_benchmark *gup)
  24 {
  25         ktime_t start_time, end_time;
  26         unsigned long i, nr_pages, addr, next;
  27         int nr;
  28         struct page **pages;
  29
  30         if (gup->size > ULONG_MAX)
  31                 return -EINVAL;
  32
  33         nr_pages = gup->size / PAGE_SIZE;
  34         pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
  35         if (!pages)
  36                 return -ENOMEM;
  37
  38         i = 0;
  39         nr = gup->nr_pages_per_call;
  40         start_time = ktime_get();
  41         for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
  42                 if (nr != gup->nr_pages_per_call)
  43                         break;
  44
  45                 next = addr + nr * PAGE_SIZE;
  46                 if (next > gup->addr + gup->size) {
  47                         next = gup->addr + gup->size;
  48                         nr = (next - addr) / PAGE_SIZE;
  49                 }
  50
  51                 switch (cmd) {
  52                 case GUP_FAST_BENCHMARK:
  53                         nr = get_user_pages_fast(addr, nr, gup->flags & 1,
  54                                                  pages + i);
  55                         break;
  56                 case GUP_LONGTERM_BENCHMARK:
  57                         nr = get_user_pages(addr, nr,
  58                                             (gup->flags & 1) | FOLL_LONGTERM,
  59                                             pages + i, NULL);
  60                         break;
  61                 case GUP_BENCHMARK:
  62                         nr = get_user_pages(addr, nr, gup->flags & 1, pages + i,
  63                                             NULL);
  64                         break;
  65                 default:
  66                         return -1;
  67                 }
  68
  69                 if (nr <= 0)
  70                         break;
  71                 i += nr;
  72         }
  73         end_time = ktime_get();
  74
  75         gup->get_delta_usec = ktime_us_delta(end_time, start_time);
  76         gup->size = addr - gup->addr;
  77
  78         start_time = ktime_get();
  79         for (i = 0; i < nr_pages; i++) {
  80                 if (!pages[i])
  81                         break;
  82                 put_page(pages[i]);
  83         }
  84         end_time = ktime_get();
  85         gup->put_delta_usec = ktime_us_delta(end_time, start_time);
  86
  87         kvfree(pages);
  88         return 0;
  89 }
  90
  91 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  92                 unsigned long arg)
  93 {
  94         struct gup_benchmark gup;
  95         int ret;
  96
  97         switch (cmd) {
  98         case GUP_FAST_BENCHMARK:
  99         case GUP_LONGTERM_BENCHMARK:
 100         case GUP_BENCHMARK:
 101                 break;
 102         default:
 103                 return -EINVAL;
 104         }
 105
 106         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
 107                 return -EFAULT;
 108
 109         ret = __gup_benchmark_ioctl(cmd, &gup);
 110         if (ret)
 111                 return ret;
 112
 113         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
 114                 return -EFAULT;
 115
 116         return 0;
 117 }
 118
 119 static const struct file_operations gup_benchmark_fops = {
 120         .open = nonseekable_open,
 121         .unlocked_ioctl = gup_benchmark_ioctl,
 122 };
 123
 124 static int gup_benchmark_init(void)
 125 {
 126         debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 127                                    &gup_benchmark_fops);
 128
 129         return 0;
 130 }
 131
 132 late_initcall(gup_benchmark_init);