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_longterm(addr, nr, gup->flags & 1,
  58                                                      pages + i, NULL);
  59                         break;
  60                 case GUP_BENCHMARK:
  61                         nr = get_user_pages(addr, nr, gup->flags & 1, pages + i,
  62                                             NULL);
  63                         break;
  64                 default:
  65                         return -1;
  66                 }
  67
  68                 if (nr <= 0)
  69                         break;
  70                 i += nr;
  71         }
  72         end_time = ktime_get();
  73
  74         gup->get_delta_usec = ktime_us_delta(end_time, start_time);
  75         gup->size = addr - gup->addr;
  76
  77         start_time = ktime_get();
  78         for (i = 0; i < nr_pages; i++) {
  79                 if (!pages[i])
  80                         break;
  81                 put_page(pages[i]);
  82         }
  83         end_time = ktime_get();
  84         gup->put_delta_usec = ktime_us_delta(end_time, start_time);
  85
  86         kvfree(pages);
  87         return 0;
  88 }
  89
  90 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  91                 unsigned long arg)
  92 {
  93         struct gup_benchmark gup;
  94         int ret;
  95
  96         switch (cmd) {
  97         case GUP_FAST_BENCHMARK:
  98         case GUP_LONGTERM_BENCHMARK:
  99         case GUP_BENCHMARK:
 100                 break;
 101         default:
 102                 return -EINVAL;
 103         }
 104
 105         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
 106                 return -EFAULT;
 107
 108         ret = __gup_benchmark_ioctl(cmd, &gup);
 109         if (ret)
 110                 return ret;
 111
 112         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
 113                 return -EFAULT;
 114
 115         return 0;
 116 }
 117
 118 static const struct file_operations gup_benchmark_fops = {
 119         .open = nonseekable_open,
 120         .unlocked_ioctl = gup_benchmark_ioctl,
 121 };
 122
 123 static int gup_benchmark_init(void)
 124 {
 125         void *ret;
 126
 127         ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 128                         &gup_benchmark_fops);
 129         if (!ret)
 130                 pr_warn("Failed to create gup_benchmark in debugfs");
 131
 132         return 0;
 133 }
 134
 135 late_initcall(gup_benchmark_init);