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         int ret = 0;
  30
  31         if (gup->size > ULONG_MAX)
  32                 return -EINVAL;
  33
  34         nr_pages = gup->size / PAGE_SIZE;
  35         pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
  36         if (!pages)
  37                 return -ENOMEM;
  38
  39         i = 0;
  40         nr = gup->nr_pages_per_call;
  41         start_time = ktime_get();
  42         for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
  43                 if (nr != gup->nr_pages_per_call)
  44                         break;
  45
  46                 next = addr + nr * PAGE_SIZE;
  47                 if (next > gup->addr + gup->size) {
  48                         next = gup->addr + gup->size;
  49                         nr = (next - addr) / PAGE_SIZE;
  50                 }
  51
  52                 /* Filter out most gup flags: only allow a tiny subset here: */
  53                 gup->flags &= FOLL_WRITE;
  54
  55                 switch (cmd) {
  56                 case GUP_FAST_BENCHMARK:
  57                         nr = get_user_pages_fast(addr, nr, gup->flags,
  58                                                  pages + i);
  59                         break;
  60                 case GUP_LONGTERM_BENCHMARK:
  61                         nr = get_user_pages(addr, nr,
  62                                             gup->flags | FOLL_LONGTERM,
  63                                             pages + i, NULL);
  64                         break;
  65                 case GUP_BENCHMARK:
  66                         nr = get_user_pages(addr, nr, gup->flags, pages + i,
  67                                             NULL);
  68                         break;
  69                 default:
  70                         kvfree(pages);
  71                         ret = -EINVAL;
  72                         goto out;
  73                 }
  74
  75                 if (nr <= 0)
  76                         break;
  77                 i += nr;
  78         }
  79         end_time = ktime_get();
  80
  81         gup->get_delta_usec = ktime_us_delta(end_time, start_time);
  82         gup->size = addr - gup->addr;
  83
  84         start_time = ktime_get();
  85         for (i = 0; i < nr_pages; i++) {
  86                 if (!pages[i])
  87                         break;
  88                 put_page(pages[i]);
  89         }
  90         end_time = ktime_get();
  91         gup->put_delta_usec = ktime_us_delta(end_time, start_time);
  92
  93         kvfree(pages);
  94 out:
  95         return ret;
  96 }
  97
  98 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
  99                 unsigned long arg)
 100 {
 101         struct gup_benchmark gup;
 102         int ret;
 103
 104         switch (cmd) {
 105         case GUP_FAST_BENCHMARK:
 106         case GUP_LONGTERM_BENCHMARK:
 107         case GUP_BENCHMARK:
 108                 break;
 109         default:
 110                 return -EINVAL;
 111         }
 112
 113         if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
 114                 return -EFAULT;
 115
 116         ret = __gup_benchmark_ioctl(cmd, &gup);
 117         if (ret)
 118                 return ret;
 119
 120         if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
 121                 return -EFAULT;
 122
 123         return 0;
 124 }
 125
 126 static const struct file_operations gup_benchmark_fops = {
 127         .open = nonseekable_open,
 128         .unlocked_ioctl = gup_benchmark_ioctl,
 129 };
 130
 131 static int gup_benchmark_init(void)
 132 {
 133         debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 134                                    &gup_benchmark_fops);
 135
 136         return 0;
 137 }
 138
 139 late_initcall(gup_benchmark_init);