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64801d19eb
The MAP_HUGETLB ("-H" option) of gup_benchmark fails:
$ sudo ./gup_benchmark -H
mmap: Invalid argument
This is because gup_benchmark.c is passing in a file descriptor to
mmap(), but the fd came from opening up the /dev/zero file. This
confuses the mmap syscall implementation, which thinks that, if the
caller did not specify MAP_ANONYMOUS, then the file must be a huge page
file. So it attempts to verify that the file really is a huge page
file, as you can see here:
ksys_mmap_pgoff()
{
if (!(flags & MAP_ANONYMOUS)) {
retval = -EINVAL;
if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
goto out_fput; /* THIS IS WHERE WE END UP */
else if (flags & MAP_HUGETLB) {
...proceed normally, /dev/zero is ok here...
...and of course is_file_hugepages() returns "false" for the /dev/zero
file.
The problem is that the user space program, gup_benchmark.c, really just
wants anonymous memory here. The simplest way to get that is to pass
MAP_ANONYMOUS whenever MAP_HUGETLB is specified, so that's what this
patch does.
Link: http://lkml.kernel.org/r/20191021212435.398153-2-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
121 lines
2.4 KiB
C
121 lines
2.4 KiB
C
#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <linux/types.h>
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#define MB (1UL << 20)
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#define PAGE_SIZE sysconf(_SC_PAGESIZE)
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#define GUP_FAST_BENCHMARK _IOWR('g', 1, struct gup_benchmark)
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#define GUP_LONGTERM_BENCHMARK _IOWR('g', 2, struct gup_benchmark)
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#define GUP_BENCHMARK _IOWR('g', 3, struct gup_benchmark)
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struct gup_benchmark {
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__u64 get_delta_usec;
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__u64 put_delta_usec;
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__u64 addr;
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__u64 size;
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__u32 nr_pages_per_call;
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__u32 flags;
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__u64 expansion[10]; /* For future use */
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};
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int main(int argc, char **argv)
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{
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struct gup_benchmark gup;
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unsigned long size = 128 * MB;
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int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
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int cmd = GUP_FAST_BENCHMARK, flags = MAP_PRIVATE;
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char *file = "/dev/zero";
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char *p;
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while ((opt = getopt(argc, argv, "m:r:n:f:tTLUwSH")) != -1) {
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switch (opt) {
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case 'm':
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size = atoi(optarg) * MB;
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break;
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case 'r':
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repeats = atoi(optarg);
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break;
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case 'n':
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nr_pages = atoi(optarg);
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break;
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case 't':
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thp = 1;
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break;
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case 'T':
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thp = 0;
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break;
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case 'L':
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cmd = GUP_LONGTERM_BENCHMARK;
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break;
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case 'U':
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cmd = GUP_BENCHMARK;
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break;
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case 'w':
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write = 1;
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break;
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case 'f':
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file = optarg;
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break;
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case 'S':
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flags &= ~MAP_PRIVATE;
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flags |= MAP_SHARED;
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break;
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case 'H':
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flags |= (MAP_HUGETLB | MAP_ANONYMOUS);
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break;
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default:
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return -1;
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}
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}
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filed = open(file, O_RDWR|O_CREAT);
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if (filed < 0) {
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perror("open");
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exit(filed);
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}
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gup.nr_pages_per_call = nr_pages;
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gup.flags = write;
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fd = open("/sys/kernel/debug/gup_benchmark", O_RDWR);
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if (fd == -1)
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perror("open"), exit(1);
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p = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, filed, 0);
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if (p == MAP_FAILED)
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perror("mmap"), exit(1);
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gup.addr = (unsigned long)p;
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if (thp == 1)
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madvise(p, size, MADV_HUGEPAGE);
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else if (thp == 0)
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madvise(p, size, MADV_NOHUGEPAGE);
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for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
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p[0] = 0;
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for (i = 0; i < repeats; i++) {
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gup.size = size;
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if (ioctl(fd, cmd, &gup))
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perror("ioctl"), exit(1);
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printf("Time: get:%lld put:%lld us", gup.get_delta_usec,
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gup.put_delta_usec);
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if (gup.size != size)
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printf(", truncated (size: %lld)", gup.size);
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printf("\n");
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}
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return 0;
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}
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