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