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