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 get_delta_usec;
  12         __u64 put_delta_usec;
  13         __u64 addr;
  14         __u64 size;
  15         __u32 nr_pages_per_call;
  16         __u32 flags;
  17         __u64 expansion[10];    /* For future use */
  18 };
  19
  20 static int __gup_benchmark_ioctl(unsigned int cmd,
  21                 struct gup_benchmark *gup)
  22 {
  23         ktime_t start_time, end_time;
  24         unsigned long i, nr_pages, addr, next;
  25         int nr;
  26         struct page **pages;
  27
  28         nr_pages = gup->size / PAGE_SIZE;
  29         pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
  30         if (!pages)
  31                 return -ENOMEM;
  32
  33         i = 0;
  34         nr = gup->nr_pages_per_call;
  35         start_time = ktime_get();
  36         for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
  37                 if (nr != gup->nr_pages_per_call)
  38                         break;
  39
  40                 next = addr + nr * PAGE_SIZE;
  41                 if (next > gup->addr + gup->size) {
  42                         next = gup->addr + gup->size;
  43                         nr = (next - addr) / PAGE_SIZE;
  44                 }
  45
  46                 nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
  47                 if (nr <= 0)
  48                         break;
  49                 i += nr;
  50         }
  51         end_time = ktime_get();
  52
  53         gup->get_delta_usec = ktime_us_delta(end_time, start_time);
  54         gup->size = addr - gup->addr;
  55
  56         start_time = ktime_get();
  57         for (i = 0; i < nr_pages; i++) {
  58                 if (!pages[i])
  59                         break;
  60                 put_page(pages[i]);
  61         }
  62         end_time = ktime_get();
  63         gup->put_delta_usec = ktime_us_delta(end_time, start_time);
  64
  65         kvfree(pages);
  66         return 0;
  67 }
  68
  69 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  70                 unsigned long arg)
  71 {
  72         struct gup_benchmark gup;
  73         int ret;
  74
  75         if (cmd != GUP_FAST_BENCHMARK)
  76                 return -EINVAL;
  77
  78         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
  79                 return -EFAULT;
  80
  81         ret = __gup_benchmark_ioctl(cmd, &gup);
  82         if (ret)
  83                 return ret;
  84
  85         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
  86                 return -EFAULT;
  87
  88         return 0;
  89 }
  90
  91 static const struct file_operations gup_benchmark_fops = {
  92         .open = nonseekable_open,
  93         .unlocked_ioctl = gup_benchmark_ioctl,
  94 };
  95
  96 static int gup_benchmark_init(void)
  97 {
  98         void *ret;
  99
 100         ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 101                         &gup_benchmark_fops);
 102         if (!ret)
 103                 pr_warn("Failed to create gup_benchmark in debugfs");
 104
 105         return 0;
 106 }
 107
 108 late_initcall(gup_benchmark_init);