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