Commit Graph

653 Commits

Author SHA1 Message Date
Azat Khuzhin
a943172b73 Add runtime detection for MADV_DONTNEED zeroes pages (mostly for qemu)
qemu does not support this, yet [1], and you can get very tricky assert
if you will run program with jemalloc in use under qemu:

    <jemalloc>: ../contrib/jemalloc/src/extent.c:1195: Failed assertion: "p[i] == 0"

  [1]: https://patchwork.kernel.org/patch/10576637/

Here is a simple example that shows the problem [2]:

    // Gist to check possible issues with MADV_DONTNEED
    // For example it does not supported by qemu user
    // There is a patch for this [1], but it hasn't been applied.
    //   [1]: https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg05422.html

    #include <sys/mman.h>
    #include <stdio.h>
    #include <stddef.h>
    #include <assert.h>
    #include <string.h>

    int main(int argc, char **argv)
    {
        void *addr = mmap(NULL, 1<<16, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
        if (addr == MAP_FAILED) {
            perror("mmap");
            return 1;
        }
        memset(addr, 'A', 1<<16);

        if (!madvise(addr, 1<<16, MADV_DONTNEED)) {
            puts("MADV_DONTNEED does not return error. Check memory.");
            for (int i = 0; i < 1<<16; ++i) {
                assert(((unsigned char *)addr)[i] == 0);
            }
        } else {
            perror("madvise");
        }

        if (munmap(addr, 1<<16)) {
            perror("munmap");
            return 1;
        }

        return 0;
    }

  ### unpatched qemu

      $ qemu-x86_64-static /tmp/test-MADV_DONTNEED
      MADV_DONTNEED does not return error. Check memory.
      test-MADV_DONTNEED: /tmp/test-MADV_DONTNEED.c:19: main: Assertion `((unsigned char *)addr)[i] == 0' failed.
      qemu: uncaught target signal 6 (Aborted) - core dumped
      Aborted (core dumped)

  ### patched qemu (by returning ENOSYS error)

      $ qemu-x86_64 /tmp/test-MADV_DONTNEED
      madvise: Success

  ### patch for qemu to return ENOSYS

      diff --git a/linux-user/syscall.c b/linux-user/syscall.c
      index 897d20c076..5540792e0e 100644
      --- a/linux-user/syscall.c
      +++ b/linux-user/syscall.c
      @@ -11775,7 +11775,7 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
                  turns private file-backed mappings into anonymous mappings.
                  This will break MADV_DONTNEED.
                  This is a hint, so ignoring and returning success is ok.  */
      -        return 0;
      +        return ENOSYS;
       #endif
       #ifdef TARGET_NR_fcntl64
           case TARGET_NR_fcntl64:

  [2]: https://gist.github.com/azat/12ba2c825b710653ece34dba7f926ece

v2:
- review fixes
- add opt_dont_trust_madvise
v3:
- review fixes
- rename opt_dont_trust_madvise to opt_trust_madvise
2021-01-20 20:08:30 -08:00
David Goldblatt
a011c4c22d cache_bin: Separate out local and remote accesses.
This fixes an incorrect debug-mode assert:
- T1 starts an arena stats update and reads stack_head from another thread's
  cache bin, when that cache bin has 1 item in it.
- T2 allocates from that cache bin.  The cache_bin's stack_head now points to a
  NULL pointer, since the cache bin is empty.
- T1 Re-reads the cache_bin's stack_head to perform an assertion check (since it
  previously saw that the bin was empty, whatever stack_head points to should be
  non-NULL).
2021-01-08 14:18:08 -08:00
Yinan Zhang
4352cbc21c Add alignment tests for prof stats 2021-01-07 20:39:49 -08:00
Yinan Zhang
54f3351f1f Add mallctl for prof stats fetching 2021-01-07 20:39:49 -08:00
Yinan Zhang
40fa4d29d3 Track per size class internal fragmentation 2021-01-07 20:39:49 -08:00
David Goldblatt
83cad746ae prof_log: cassert(config_prof) in public functions
This lets the compiler infer that the code is dead in builds where profiling is
enabled, saving on space there.
2021-01-04 14:55:49 -08:00
Yinan Zhang
4557c0a67d Enable ctl on partial mib and partial name 2020-12-18 10:39:58 -08:00
Yinan Zhang
006dd0414e Add partial name-to-mib functionality 2020-12-18 10:39:58 -08:00
Yinan Zhang
f2e1a5be77 Do not fail on partial ctl path for ctl_nametomib()
We do not fail on partial ctl path when the given `mib` array is
shorter than the given name, and we should keep the behavior the
same in the reverse case, which I feel is also the more natural way.
2020-12-18 10:39:58 -08:00
David Goldblatt
1e3b8636ff HPA: Remove unused malloc_conf options. 2020-12-08 12:10:48 -08:00
Yinan Zhang
e82771807e Cache mallctl mib for batch allocation stress test 2020-12-07 09:10:11 -08:00
Yinan Zhang
0dfdd31e0f Add tiny batch size to batch allocation stress test 2020-12-07 09:10:11 -08:00
David Goldblatt
f51948d9e1 psset unit test: fix a bug.
The next commit adds assertions that reveal a bug in the test code
(double-free).  Fix it.
2020-12-07 06:21:08 -08:00
David Goldblatt
54c94c1679 flat bitmap: add scount / ucount functions.
These can compute the number or set or unset bits in a subrange of the bitmap.
2020-12-07 06:21:08 -08:00
David Goldblatt
734e72ce8f bit_util: Guarantee popcount's presence.
Implement popcount generically, so that we can rely on it being present.
2020-12-07 06:21:08 -08:00
David Goldblatt
d9f7e6c668 hpdata: Add a test.
We're about to make the functionality here more complicated; testing hpdata
directly (rather than relying on user's tests) will make debugging easier.
2020-12-07 06:21:08 -08:00
David Goldblatt
f7cf23aa4d psset: Relegate alloc/dalloc to test code.
This is no longer part of the "core" functionality; we only need the stub
implementations as an end-to-end test of hpdata + psset interactions when
metadata is being modified.  Treat them accordingly.
2020-12-07 06:21:08 -08:00
David Goldblatt
ca30b5db2b Introduce hpdata_t.
Using an edata_t both for hugepages and the allocations within those hugepages
was convenient at first, but has outlived its usefulness.  Representing
hugepages explicitly, with their own data structure, will make future
development easier.
2020-12-07 06:21:08 -08:00
David Goldblatt
4a15008cfb HPA unit test: skip if unsupported.
Previously, we replicated the logic in hpa_supported in the test as well.
2020-12-07 06:21:08 -08:00
David Goldblatt
43af63fff4 HPA: Manage whole hugepages at a time.
This redesigns the HPA implementation to allow us to manage hugepages all at
once, locally, without relying on a global fallback.
2020-12-07 06:21:08 -08:00
David Goldblatt
c1b2a77933 psset: Move in stats.
A later change will benefit from having these functions pulled into a
psset-module set of functions.
2020-12-07 06:21:08 -08:00
David Goldblatt
d0a991d47b psset: Add insert/remove functions.
These will allow us to (for instance) move pageslabs from a psset dedicated to
not-yet-hugeified pages to one dedicated to hugeified ones.
2020-12-07 06:21:08 -08:00
David Goldblatt
ecd39418ac Add fxp: A fixed-point math library.
This will be used in the next commit to allow non-integer values for
narenas_ratio.
2020-12-04 23:48:19 -08:00
Yinan Zhang
d96e4525ad Route batch allocation of small batch size to tcache 2020-11-16 20:58:01 -08:00
Yinan Zhang
ac480136d7 Split out locality checking in batch allocation tests 2020-11-16 20:58:01 -08:00
Yinan Zhang
be5e49f4fa Add a batch mode for cache_bin_alloc() 2020-11-16 20:58:01 -08:00
Yinan Zhang
4a65f34930 Fix a cache bin test 2020-11-16 20:58:01 -08:00
Yinan Zhang
9545c2cd36 Add sample interval to prof last-N dump 2020-11-13 15:33:27 -08:00
David Goldblatt
cf2549a149 Add a per-arena oversize_threshold.
This can let manual arenas trade off memory and CPU the way auto arenas do.
2020-11-13 13:45:35 -08:00
David Goldblatt
4ca3d91e96 Rename geom_grow -> exp_grow.
This was promised in the review of the introduction of geom_grow, but would have
been painful to do there because of the series that introduced it.  Now that
those are comitted, renaming is easier.
2020-11-13 13:42:33 -08:00
David Goldblatt
03a6047111 Edata cache small: rewrite.
In previous designs, this was intended to be a sort of cache that couldn't fail.
In the current design, we want to use it just as a contention reduction
mechanism.  Rewrite it with those goals in mind.
2020-11-05 12:34:43 -08:00
David Goldblatt
1b3ee75667 Add experimental.thread.activity_callback.
This (experimental, undocumented) functionality can be used by users to track
various statistics of interest at a finer level of granularity than the thread.
2020-11-05 12:33:25 -08:00
Qi Wang
bf72188f80 Allow opt.tcache_max to accept small size classes.
Previously all the small size classes were cached.  However this has downsides
-- particularly when page size is greater than 4K (e.g. iOS), which will result
in much higher SMALL_MAXCLASS.

This change allows tcache_max to be set to lower values, to better control
resources taken by tcache.
2020-10-24 20:43:44 -07:00
David Goldblatt
d16849c91d psset: Do first-fit based on slab age.
This functions more like the serial number strategy of the ecache and
hpa_central_t.  Longer-lived slabs are more likely to continue to live for
longer in the future.
2020-10-23 11:14:34 -07:00
David Goldblatt
6599651aee PA: Use an SEC in fron of the HPA shard. 2020-10-23 11:14:34 -07:00
David Goldblatt
ea51e97bb8 Add SEC module: a small extent cache.
This can be used to take pressure off a more centralized, worse-sharded
allocator without requiring a full break of the arena abstraction.
2020-10-23 11:14:34 -07:00
David Goldblatt
534504d4a7 HPA: add size-exclusion functionality.
I.e. only allowing allocations under or over certain sizes.
2020-10-23 11:14:34 -07:00
David Goldblatt
1c7da33317 HPA: Tie components into a PAI implementation. 2020-10-23 11:14:34 -07:00
Qi Wang
c8209150f9 Switch from opt.lg_tcache_max to opt.tcache_max
Though for convenience, keep parsing lg_tcache_max.
2020-10-22 20:40:41 -07:00
Qi Wang
3de19ba401 Eagerly detect double free and sized dealloc bugs for large sizes. 2020-10-15 10:03:16 -07:00
David Goldblatt
21b70cb540 Add hpa_central module
This will be the centralized component of the coming hugepage allocator; the
source of larger chunks of memory from which smaller ones can be obtained.
2020-10-05 19:55:57 -07:00
David Goldblatt
2a6ba121b5 PRNG test: cleanups.
Since we no longer have both atomic and non-atomic variants, there's no reason
to try to test both.
2020-10-05 19:55:57 -07:00
David Goldblatt
9e6aa77ab9 PRNG: Remove atomic functionality.
These had no uses and complicated the API.  As a rule we now expect to only use
thread-local randomization for contention-reduction reasons, so we only pay the
API costs and never get the functionality benefits.
2020-10-05 19:55:57 -07:00
David Goldblatt
259c5e3e8f psset: Add stats 2020-09-18 12:39:25 -07:00
David Goldblatt
018b162d67 Add psset: a set of pageslabs.
This introduces a new sort of edata_t; a pageslab, and a set to manage them.
This is part of a series of a commits to implement a hugepage allocator; the
pageset will be per-arena, and track small page allocations requests within a
larger extent allocated from a centralized hugepage allocator.
2020-09-18 12:39:25 -07:00
David Goldblatt
ed99d300b9 Flat bitmap: Add longest-range computation.
This will come in handy in the (upcoming) page-slab set assertions.
2020-09-18 12:39:25 -07:00
David Goldblatt
e034500698 Edata: rename "ranged" bit to "pai".
This better represents its intended purpose; the hugepage allocator design
evolved away from needing contiguity of hugepage virtual address space.
2020-09-18 12:39:25 -07:00
Yinan Zhang
09eda2c9b6 Add unit tests for usize in prof recent records 2020-09-09 13:31:35 -07:00
David Goldblatt
131b1b5338 Rename ecache_grow -> geom_grow.
We're about to start using it outside of the ecaches, in the HPA central
allocator.
2020-08-19 16:53:21 -07:00
David Goldblatt
b399463fba flat_bitmap unit test: Silence a warning. 2020-08-17 12:50:27 -07:00