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authorH.J. Lu <hjl.tools@gmail.com>2016-04-23 06:05:01 -0700
committerH.J. Lu <hjl.tools@gmail.com>2016-04-23 06:05:15 -0700
commit2bc983b78c215765979a29a2e98b0cc01791c2d1 (patch)
treedd39b724f90f6a70a28ee4fd06d1edf8aae743f2 /elf/tst-audit11.c
parent00277a3f81bf023d4562da485f62efe5b5b30388 (diff)
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Reduce number of mmap calls from __libc_memalign in ld.so
__libc_memalign in ld.so allocates one page at a time and tries to
optimize consecutive __libc_memalign calls by hoping that the next
mmap is after the current memory allocation.

However, the kernel hands out mmap addresses in top-down order, so
this optimization in practice never happens, with the result that we
have more mmap calls and waste a bunch of space for each __libc_memalign.

This change makes __libc_memalign to mmap one page extra.  Worst case,
the kernel never puts a backing page behind it, but best case it allows
__libc_memalign to operate much much better.  For elf/tst-align --direct,
it reduces number of mmap calls from 12 to 9.

	* elf/dl-minimal.c (__libc_memalign): Mmap one extra page.
Diffstat (limited to 'elf/tst-audit11.c')
0 files changed, 0 insertions, 0 deletions