FAQ
Edit report at https://bugs.php.net/bug.php?id=70984&edit=1

  ID: 70984
  Updated by: rasmus@php.net
  Reported by: arjen@react.com
  Summary: Script extreme slow compared to 5.6, MAP_HUGETLB
                      problem?
-Status: Open
+Status: Analyzed
  Type: Bug
  Package: Scripting Engine problem
  Operating System: Linux
  PHP Version: 7.0.0RC8
  Block user comment: N
  Private report: N

  New Comment:

Just to verify that it is due to the lack of huge pages, can you configure some and re-run your test. Something like:

     sysctl -w vm.nr_hugepages=256


Previous Comments:
------------------------------------------------------------------------
[2015-11-27 12:54:26] arjen@react.com

Description:
------------
Testcase runs in 6.7 sec.
1.7 sec in PHP 5.6.

strace reports lots of ENOMEM (Cannot allocate memory) warnings:

munmap(0x7fd131400000, 2097152) = 0
mmap(NULL, 2097152, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 2097152, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd131400000
madvise(0x7fd131400000, 2097152, MADV_HUGEPAGE) = 0
munmap(0x7fd131400000, 2097152) = 0
mmap(NULL, 2097152, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 2097152, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd131400000
madvise(0x7fd131400000, 2097152, MADV_HUGEPAGE) = 0
[....]

Ultimately the memory allocation succeeds. With bigger javascript inputs (it's a javascript minifier), running time can be in 10-60 minutes, compared to 1-5 minutes under 5.6.

The PHP binary is compiled on a host with HUGETLB support, however the target host (systemd-container) has not Hugepages (configured). 5.6 testing was done with same memory amount. There is enough (normal) free memory.

cat /proc/meminfo
[..]
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0



Test script:
---------------
https://gist.github.com/arjenschol/49a847c07154b51130b2

Expected result:
----------------
Execution at least as fast as 5.6.

Actual result:
--------------
3-4x slower compared to 5.6.


------------------------------------------------------------------------

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postedNov 27, '15 at 12:54p
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