git: libc - Improve realloc() performance.
matthias_play at gmx.net
Fri Feb 19 03:47:07 PST 2016
this reminds me to ask if DragionFly is effected by the recently
discovered stack-based buffer overflow bug in glibc:
On 17.02.16 19:39, Matthew Dillon wrote:
> commit 07a8ffeaab3fc830679c6836a6ee198ad1a3275f
> Author: Matthew Dillon <dillon at apollo.backplane.com>
> Date: Tue Feb 16 20:40:44 2016 -0800
> libc - Improve realloc() performance.
> * Oversized free()'s <= 1MB will be cached in a 16-entry array. Any oversized
> allocation can make use of the cache, even if available cache entries are
> significantly larger than desired, in order to accomodate application
> buffer-growing behavior. This means that applications which realloc() a
> lot (at least as long as the buffer is <= 1MB) will wind up being handed
> a ~1MB buffer quite frequently, eliminating new mmap() operations.
> * Keeps track of the excess in oversized allocations and will garbage-collect
> it if it grows too large (typically > 16MB). This is primarily what allows
> us to be generous.
> * realloc() will attempt to use MAP_TRYFIXED to extend an oversized allocation
> before giving up and remapping it.
> * Improves programs which realloc() or malloc()/free() large numbers of
> oversized blocks by reducing or eliminating mmap()/munmap() calls.
> Summary of changes:
> lib/libc/stdlib/nmalloc.c | 250 +++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 227 insertions(+), 23 deletions(-)
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