cosmopolitan/test/libc/intrin/mremap_test.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2024 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/sysv/consts/mremap.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/timespec.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/maps.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/mremap.h"
#include "libc/sysv/consts/prot.h"
#include "libc/testlib/testlib.h"

void SetUpOnce(void) {
  if (!IsLinux() && !IsNetbsd()) {
    tinyprint(2, "warning: skipping mremap() tests on this os\n", NULL);
    exit(0);
  }
}

TEST(mremap, dontMove_hasRoom_itMoves) {
  if (IsNetbsd())
    return;  // NetBSD requires MREMAP_MAYMOVE
  char *p;
  int pagesz = getpagesize();
  ASSERT_NE(MAP_FAILED,
            (p = mmap(__maps_randaddr(), pagesz, PROT_READ | PROT_EXEC,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)));
  EXPECT_TRUE(testlib_memoryexists(p));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz));
  ASSERT_SYS(0, p, mremap(p, pagesz, pagesz * 2, 0));
  EXPECT_TRUE(testlib_memoryexists(p));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz));
  ASSERT_SYS(0, 0, munmap(p, pagesz * 2));
  EXPECT_FALSE(testlib_memoryexists(p));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz));
}

TEST(mremap, dontMove_noRoom_itFailsWithEnomem) {
  if (IsNetbsd())
    return;  // NetBSD requires MREMAP_MAYMOVE
  char *p;
  int pagesz = getpagesize();
  ASSERT_NE(MAP_FAILED,
            (p = mmap(__maps_randaddr(), pagesz * 2, PROT_READ | PROT_EXEC,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
  ASSERT_SYS(ENOMEM, MAP_FAILED, mremap(p, pagesz, pagesz * 3, 0));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
  ASSERT_SYS(0, 0, munmap(p, pagesz * 2));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
}

TEST(mremap, mayMove_noRoom_itRelocates) {
  char *p, *p2;
  int pagesz = getpagesize();
  ASSERT_NE(MAP_FAILED,
            (p = mmap(__maps_randaddr(), pagesz * 2, PROT_READ | PROT_EXEC,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
  ASSERT_NE(MAP_FAILED, (p2 = mremap(p, pagesz, pagesz * 3, MREMAP_MAYMOVE)));
  ASSERT_NE(p, p2);
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_TRUE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
  EXPECT_TRUE(testlib_memoryexists(p2 + pagesz * 0));
  EXPECT_TRUE(testlib_memoryexists(p2 + pagesz * 1));
  EXPECT_TRUE(testlib_memoryexists(p2 + pagesz * 2));
  ASSERT_SYS(0, 0, munmap(p + pagesz, pagesz));
  ASSERT_SYS(0, 0, munmap(p2, pagesz * 3));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 0));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p + pagesz * 2));
  EXPECT_FALSE(testlib_memoryexists(p2 + pagesz * 0));
  EXPECT_FALSE(testlib_memoryexists(p2 + pagesz * 1));
  EXPECT_FALSE(testlib_memoryexists(p2 + pagesz * 2));
}

// demonstrate value of mremap() system call
//
//       mmap(1'048'576) took 1'130 ns
//     mremap(1'048'576 -> 2'097'152) took 3'117 ns
//     mremap(2'097'152 -> 1'048'576) took 3'596 ns
//     mremap(1'048'576 -> 2'097'152) took 796'381 ns [simulated]
//     munmap(2'097'152) took 50'020 ns
//

TEST(mremap, bench) {
#define N 10
  long size = 1024 * 1024;
  char *rollo = __maps_randaddr();
  char *addr[N];

  // create mappings
  struct timespec ts1 = timespec_real();
  for (long i = 0; i < N; ++i)
    if ((addr[i] = mmap((rollo += size), size, PROT_READ | PROT_WRITE,
                        MAP_ANONYMOUS | MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
      kprintf("first mmap failed: %m\n");
      exit(1);
    }
  kprintf("mmap(%'zu) took %'ld ns\n", size,
          timespec_tonanos(timespec_sub(timespec_real(), ts1)) / N);

  // use mremap to grow mappings
  ts1 = timespec_real();
  for (long i = 0; i < N; ++i)
    if ((addr[i] = mremap(addr[i], size, size * 2, MREMAP_MAYMOVE)) ==
        MAP_FAILED) {
      kprintf("grow mremap failed: %m\n");
      exit(1);
    }
  kprintf("mremap(%'zu -> %'zu) took %'ld ns\n", size, size * 2,
          timespec_tonanos(timespec_sub(timespec_real(), ts1)) / N);

  // use mremap to shrink mappings
  ts1 = timespec_real();
  for (long i = 0; i < N; ++i)
    if (mremap(addr[i], size * 2, size, 0) != addr[i]) {
      kprintf("shrink mremap failed: %m\n");
      exit(1);
    }
  kprintf("mremap(%'zu -> %'zu) took %'ld ns\n", size * 2, size,
          timespec_tonanos(timespec_sub(timespec_real(), ts1)) / N);

  // do the thing that mremap is trying to optimize
  ts1 = timespec_real();
  for (long i = 0; i < N; ++i) {
    char *addr2;
    if ((addr2 = mmap(0, size * 2, PROT_READ | PROT_WRITE,
                      MAP_ANONYMOUS | MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
      kprintf("simulated mmap failed: %m\n");
      exit(1);
    }
    memmove(addr2, addr[i], size);
    if (munmap(addr[i], size)) {
      kprintf("simulated munmap failed: %m\n");
      exit(1);
    }
    addr[i] = addr2;
  }
  kprintf("mremap(%'zu -> %'zu) took %'ld ns [simulated]\n", size, size * 2,
          timespec_tonanos(timespec_sub(timespec_real(), ts1)) / N);

  // unmap mappings
  ts1 = timespec_real();
  for (long i = 0; i < N; ++i)
    if (munmap(addr[i], size * 2)) {
      kprintf("munmap failed: %m\n");
      exit(1);
    }
  kprintf("munmap(%'zu) took %'ld ns\n", size * 2,
          timespec_tonanos(timespec_sub(timespec_real(), ts1)) / N);
}