On 2/20/23 17:16, Phil Bouchard via Std-Proposals wrote:
> Yeah or you could postpone the deallocations when the CPU idles, just
> like a garbage collector.
>
> Whatever the reason I think it's imperative to override application-wide
> default allocators.

Mix that with thread-local, allocation rate-based and type-based and
you'll have a blinking fast application.


> On 2/20/23 17:09, Frederick Virchanza Gotham via Std-Proposals wrote:
>> On Mon, Feb 20, 2023 at 7:51 PM Julien Villemure-Fréchette via
>> Std-Proposals <std-proposals_at_[hidden]> wrote:
>>>
>>> global operator new and delete can be replaced by a non inline, non
>>> static global operator new with equivalent signature
>>
>>
>> I wrote a program one time and I wanted it to be lightning fast, and
>> so I overloaded 'new' so that it allocated massive chunks at a time,
>> and 'delete' didn't do anything. I of course was wasting memory but it
>> was fine as I had enough RAM. Here's what I did:
>>
>> #include <cstddef> // size_t
>> #include <cstdlib> // malloc
>> #include <new> // required otherwise we get a compiler error
>> for the 'noexcept'
>>
>> using std::size_t;
>>
>> size_t g_total_allocation = 0u;
>>
>> inline void *Implementation_Global_New(size_t size) noexcept
>> {
>> size += 8u - (size % 8u);
>>
>> static size_t constexpr bytes_at_a_time = 10485760u; /* We
>> allocate 10 megabytes at a time */
>>
>> if ( size > bytes_at_a_time ) return nullptr;
>>
>> static void *p = nullptr;
>>
>> static size_t bytes_allocated_so_far = 0u;
>>
>> for (; /* ever */ ;)
>> {
>> if ( nullptr == p )
>> {
>> p = std::malloc(bytes_at_a_time);
>>
>> if ( nullptr == p ) return nullptr;
>>
>> g_total_allocation += bytes_at_a_time;
>> }
>>
>> if ( (bytes_allocated_so_far + size) > bytes_at_a_time )
>> {
>> p = nullptr;
>>
>> bytes_allocated_so_far = 0u;
>> }
>> else
>> {
>> break;
>> }
>> }
>>
>> void *const retval = static_cast<char*>(p) + bytes_allocated_so_far;
>>
>> bytes_allocated_so_far += size;
>>
>> return retval;
>> }
>>
>> void *operator new (size_t const size) noexcept { return
>> Implementation_Global_New(size); }
>> void *operator new[](size_t const size) noexcept { return
>> Implementation_Global_New(size); }
>> void operator delete (void *const p) noexcept { /* Do Nothing */ }
>> void operator delete[](void *const p) noexcept { /* Do Nothing */ }
>

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