[PATCH v4 3/3] malloc: Add tcache path for calloc

[Guo, Wangyang]

On 11/26/2024 5:08 PM, H.J. Lu wrote:

> On Tue, Nov 26, 2024 at 3:37 PM Wangyang Guo <wangyang.guo@intel.com> wrote:
>> This commit add tcache support in calloc() which can largely improve
>> the performance of small size allocation, especially in multi-thread
>> scenario. clear_mem() and tcache_available() is split out as a helper
>> function for better reusing the code.
>>
>> Also fix tst-safe-linking failure after enabling tcache. In previous,
>> calloc() is used as a way to by-pass tcache in memory allocation and
>> trigger safe-linking check in fastbins path. With tcache enabled, it
>> needs extra workarounds to bypass tcache.
>>
>> Result of bench-malloc-thread benchmark
>>
>> Test Platform: Xeon-8380
>> Bench Function: calloc
>> Ratio: New / Original time_per_iteration (Lower is Better)
>>
>> Threads#   | Ratio
>> -----------|------
>> 1 thread   | 0.724
>> 4 threads  | 0.534
>>
> Since you are working on calloc, please try this patch to see if
> it improves performance on x86-64.
>
> Thanks.

Look like the change is within variation. For bench-malloc-thread 
benchmark, the cycles spent in this area is not very hot.

Test Platform: Xeon-8380
Bench Function: calloc
Ratio: New / Original time_per_iteration (Lower is Better)

Threads#   | Ratio
-----------|------
1 thread   | 0.993
4 threads  | 0.996