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| author |   Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-08-16 15:08:27 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-12-15 17:35:38 -0300 |
| commit | 98d5fcb8d099a1a868e032c89891c395a2f365c5 (patch) | |
| tree | 13b1a0a98165f832a5ae394b958cb749709dad1d /NEWS | |
| parent | malloc: Move mmap logic to its own function (diff) | |
| download | glibc-98d5fcb8d099a1a868e032c89891c395a2f365c5.tar.gz glibc-98d5fcb8d099a1a868e032c89891c395a2f365c5.tar.bz2 glibc-98d5fcb8d099a1a868e032c89891c395a2f365c5.zip | |
malloc: Add Huge Page support for mmap
With the morecore hook removed, there is not easy way to provide huge
pages support on with glibc allocator without resorting to transparent
huge pages. And some users and programs do prefer to use the huge pages
directly instead of THP for multiple reasons: no splitting, re-merging
by the VM, no TLB shootdowns for running processes, fast allocation
from the reserve pool, no competition with the rest of the processes
unlike THP, no swapping all, etc.
This patch extends the 'glibc.malloc.hugetlb' tunable: the value
'2' means to use huge pages directly with the system default size,
while a positive value means and specific page size that is matched
against the supported ones by the system.
Currently only memory allocated on sysmalloc() is handled, the arenas
still uses the default system page size.
To test is a new rule is added tests-malloc-hugetlb2, which run the
addes tests with the required GLIBC_TUNABLE setting. On systems without
a reserved huge pages pool, is just stress the mmap(MAP_HUGETLB)
allocation failure. To improve test coverage it is required to create
a pool with some allocated pages.
Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 8 |
1 files changed, 5 insertions, 3 deletions
@@ -93,9 +93,11 @@ Major new features: configuration. * On Linux, a new tunable, glibc.malloc.hugetlb, can be used to - make malloc issue madvise plus MADV_HUGEPAGE on mmap and sbrk calls. - Setting this might improve performance with Transparent Huge Pages madvise - mode depending of the workload. + either make malloc issue madvise plus MADV_HUGEPAGE on mmap and sbrk + or to use huge pages directly with mmap calls with the MAP_HUGETLB + flags). The former can improve performance when Transparent Huge Pages + is set to 'madvise' mode while the latter uses the system reserved + huge pages. Deprecated and removed features, and other changes affecting compatibility: |