On Wed, Feb 28, 2024 at 12:08 AM Lameter, Christopher <cl@xxxxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 27 Feb 2024, 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 ? > > > > On a host with 384 threads, 384*16 -> 6 GB of memory. > > Those things also come with corresponding memories of a couple of TB... > > > With this kind of use, we might need a shrinker... > > Yes. No point of keeping the buffers around if the core stops doing > networking. But to be done at times when there is no contention please. I yet have to see the 'contention' ? I usually see one on the zone spinlock or memcg ones when allocating/freeing pages, not on the tcp_memory_allocated atomic We can add caches for sure, we had a giant one before my patch, and this was a disaster really, for workloads with millions of TCP sockets.
