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828675421e
When calling mmap(), in general the system gives us a page but does not really allocate it until we first dereference it. And it turns out that this time is much longer than the time to perform the mmap() syscall. Unfortunately, when running with memory debugging enabled, we mmap/munmap() each object resulting in lots of such calls and a high contention on the allocator. And the first accesses to the page being done under the pool lock is extremely damaging to other threads. The simple fact of writing a 0 at the beginning of the page after allocating it and placing the POOL_LINK pointer outside of the lock is enough to boost the performance by 8x in debug mode and to save the watchdog from triggering on lock contention. This is what this patch does.