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         int ret = 0;
  30
  31         if (gup->size > ULONG_MAX)
  32                 return -EINVAL;
  33
  34         nr_pages = gup->size / PAGE_SIZE;
  35         pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
  36         if (!pages)
  37                 return -ENOMEM;
  38
  39         i = 0;
  40         nr = gup->nr_pages_per_call;
  41         start_time = ktime_get();
  42         for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
  43                 if (nr != gup->nr_pages_per_call)
  44                         break;
  45
  46                 next = addr + nr * PAGE_SIZE;
  47                 if (next > gup->addr + gup->size) {
  48                         next = gup->addr + gup->size;
  49                         nr = (next - addr) / PAGE_SIZE;
  50                 }
  51
  52                 switch (cmd) {
  53                 case GUP_FAST_BENCHMARK:
  54                         nr = get_user_pages_fast(addr, nr, gup->flags & 1,
  55                                                  pages + i);
  56                         break;
  57                 case GUP_LONGTERM_BENCHMARK:
  58                         nr = get_user_pages(addr, nr,
  59                                             (gup->flags & 1) | FOLL_LONGTERM,
  60                                             pages + i, NULL);
  61                         break;
  62                 case GUP_BENCHMARK:
  63                         nr = get_user_pages(addr, nr, gup->flags & 1, pages + i,
  64                                             NULL);
  65                         break;
  66                 default:
  67                         kvfree(pages);
  68                         ret = -EINVAL;
  69                         goto out;
  70                 }
  71
  72                 if (nr <= 0)
  73                         break;
  74                 i += nr;
  75         }
  76         end_time = ktime_get();
  77
  78         gup->get_delta_usec = ktime_us_delta(end_time, start_time);
  79         gup->size = addr - gup->addr;
  80
  81         start_time = ktime_get();
  82         for (i = 0; i < nr_pages; i++) {
  83                 if (!pages[i])
  84                         break;
  85                 put_page(pages[i]);
  86         }
  87         end_time = ktime_get();
  88         gup->put_delta_usec = ktime_us_delta(end_time, start_time);
  89
  90         kvfree(pages);
  91 out:
  92         return ret;
  93 }
  94
  95 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  96                 unsigned long arg)
  97 {
  98         struct gup_benchmark gup;
  99         int ret;
 100
 101         switch (cmd) {
 102         case GUP_FAST_BENCHMARK:
 103         case GUP_LONGTERM_BENCHMARK:
 104         case GUP_BENCHMARK:
 105                 break;
 106         default:
 107                 return -EINVAL;
 108         }
 109
 110         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
 111                 return -EFAULT;
 112
 113         ret = __gup_benchmark_ioctl(cmd, &gup);
 114         if (ret)
 115                 return ret;
 116
 117         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
 118                 return -EFAULT;
 119
 120         return 0;
 121 }
 122
 123 static const struct file_operations gup_benchmark_fops = {
 124         .open = nonseekable_open,
 125         .unlocked_ioctl = gup_benchmark_ioctl,
 126 };
 127
 128 static int gup_benchmark_init(void)
 129 {
 130         debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 131                                    &gup_benchmark_fops);
 132
 133         return 0;
 134 }
 135
 136 late_initcall(gup_benchmark_init);