Re: [PATCH] net: make SK_MEMORY_PCPU_RESERV tunable

[Adam Li]

On 2/28/2024 4:38 AM, Eric Dumazet wrote:

>>
>> sk_prot->memory_allocated points to global atomic variable:
>> atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp;
>>
>> If increasing the per-cpu cache size from 1MB to e.g. 16MB,
>> changes to sk->sk_prot->memory_allocated can be further reduced.
>> Performance may be improved on system with many cores.
> 
> This looks good, do you have any performance numbers to share ?

I ran localhost memcached test on system with 320 CPU threads,
perf shows 4% cycles spent in __sk_mem_raise_allocated() -->sk_memory_allocated().
If increasing SK_MEMORY_PCPU_RESERV to 16MB, perf cycles spent in
__sk_mem_raise_allocated() drops to 0.4%.

Thanks,
-adam