On Thu, Oct 31, 2024 at 10:19:55AM -0700, Caleb Sander wrote: > [Some people who received this message don't often get email from csander@xxxxxxxxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > On Thu, Oct 31, 2024 at 5:49 AM Louis Peens <louis.peens@xxxxxxxxxxxx> wrote: > > > > On Wed, Oct 30, 2024 at 06:23:26PM -0600, Caleb Sander Mateos wrote: > > > net_dim() is currently passed a struct dim_sample argument by value. > > > struct dim_sample is 24 bytes. Since this is greater 16 bytes, x86-64 > > > passes it on the stack. All callers have already initialized dim_sample > > > on the stack, so passing it by value requires pushing a duplicated copy > > > to the stack. Either witing to the stack and immediately reading it, or > > > perhaps dereferencing addresses relative to the stack pointer in a chain > > > of push instructions, seems to perform quite poorly. > > > > > > In a heavy TCP workload, mlx5e_handle_rx_dim() consumes 3% of CPU time, > > > 94% of which is attributed to the first push instruction to copy > > > dim_sample on the stack for the call to net_dim(): > > > // Call ktime_get() > > > 0.26 |4ead2: call 4ead7 <mlx5e_handle_rx_dim+0x47> > > > // Pass the address of struct dim in %rdi > > > |4ead7: lea 0x3d0(%rbx),%rdi > > > // Set dim_sample.pkt_ctr > > > |4eade: mov %r13d,0x8(%rsp) > > > // Set dim_sample.byte_ctr > > > |4eae3: mov %r12d,0xc(%rsp) > > > // Set dim_sample.event_ctr > > > 0.15 |4eae8: mov %bp,0x10(%rsp) > > > // Duplicate dim_sample on the stack > > > 94.16 |4eaed: push 0x10(%rsp) > > > 2.79 |4eaf1: push 0x10(%rsp) > > > 0.07 |4eaf5: push %rax > > > // Call net_dim() > > > 0.21 |4eaf6: call 4eafb <mlx5e_handle_rx_dim+0x6b> > > > > > > To allow the caller to reuse the struct dim_sample already on the stack, > > > pass the struct dim_sample by reference to net_dim(). > > > > > > Signed-off-by: Caleb Sander Mateos <csander@xxxxxxxxxxxxxxx> > > > --- > > > Documentation/networking/net_dim.rst | 2 +- > > > drivers/net/ethernet/amazon/ena/ena_netdev.c | 2 +- > > > drivers/net/ethernet/broadcom/bcmsysport.c | 2 +- > > > drivers/net/ethernet/broadcom/bnxt/bnxt.c | 4 ++-- > > > drivers/net/ethernet/broadcom/genet/bcmgenet.c | 2 +- > > > drivers/net/ethernet/freescale/enetc/enetc.c | 2 +- > > > drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 4 ++-- > > > drivers/net/ethernet/intel/ice/ice_txrx.c | 4 ++-- > > > drivers/net/ethernet/intel/idpf/idpf_txrx.c | 4 ++-- > > > drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c | 2 +- > > > drivers/net/ethernet/mediatek/mtk_eth_soc.c | 4 ++-- > > > drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c | 4 ++-- > > > drivers/net/ethernet/netronome/nfp/nfd3/dp.c | 4 ++-- > > > drivers/net/ethernet/netronome/nfp/nfdk/dp.c | 4 ++-- > > > drivers/net/ethernet/pensando/ionic/ionic_txrx.c | 2 +- > > > drivers/net/virtio_net.c | 2 +- > > > drivers/soc/fsl/dpio/dpio-service.c | 2 +- > > > include/linux/dim.h | 2 +- > > > lib/dim/net_dim.c | 10 +++++----- > > > 19 files changed, 31 insertions(+), 31 deletions(-) > > > > > --- snip -- > > > > > diff --git a/drivers/net/ethernet/netronome/nfp/nfd3/dp.c b/drivers/net/ethernet/netronome/nfp/nfd3/dp.c > > > index d215efc6cad0..f1c6c47564b1 100644 > > > --- a/drivers/net/ethernet/netronome/nfp/nfd3/dp.c > > > +++ b/drivers/net/ethernet/netronome/nfp/nfd3/dp.c > > > @@ -1177,11 +1177,11 @@ int nfp_nfd3_poll(struct napi_struct *napi, int budget) > > > pkts = r_vec->rx_pkts; > > > bytes = r_vec->rx_bytes; > > > } while (u64_stats_fetch_retry(&r_vec->rx_sync, start)); > > > > > > dim_update_sample(r_vec->event_ctr, pkts, bytes, &dim_sample); > > > - net_dim(&r_vec->rx_dim, dim_sample); > > > + net_dim(&r_vec->rx_dim, &dim_sample); > > > } > > > > > > if (r_vec->nfp_net->tx_coalesce_adapt_on && r_vec->tx_ring) { > > > struct dim_sample dim_sample = {}; > > > unsigned int start; > > > @@ -1192,11 +1192,11 @@ int nfp_nfd3_poll(struct napi_struct *napi, int budget) > > > pkts = r_vec->tx_pkts; > > > bytes = r_vec->tx_bytes; > > > } while (u64_stats_fetch_retry(&r_vec->tx_sync, start)); > > > > > > dim_update_sample(r_vec->event_ctr, pkts, bytes, &dim_sample); > > > - net_dim(&r_vec->tx_dim, dim_sample); > > > + net_dim(&r_vec->tx_dim, &dim_sample); > > > } > > > > > > return pkts_polled; > > > } > > > > > > diff --git a/drivers/net/ethernet/netronome/nfp/nfdk/dp.c b/drivers/net/ethernet/netronome/nfp/nfdk/dp.c > > > index dae5af7d1845..ebeb6ab4465c 100644 > > > --- a/drivers/net/ethernet/netronome/nfp/nfdk/dp.c > > > +++ b/drivers/net/ethernet/netronome/nfp/nfdk/dp.c > > > @@ -1287,11 +1287,11 @@ int nfp_nfdk_poll(struct napi_struct *napi, int budget) > > > pkts = r_vec->rx_pkts; > > > bytes = r_vec->rx_bytes; > > > } while (u64_stats_fetch_retry(&r_vec->rx_sync, start)); > > > > > > dim_update_sample(r_vec->event_ctr, pkts, bytes, &dim_sample); > > > - net_dim(&r_vec->rx_dim, dim_sample); > > > + net_dim(&r_vec->rx_dim, &dim_sample); > > > } > > > > > > if (r_vec->nfp_net->tx_coalesce_adapt_on && r_vec->tx_ring) { > > > struct dim_sample dim_sample = {}; > > > unsigned int start; > > > @@ -1302,11 +1302,11 @@ int nfp_nfdk_poll(struct napi_struct *napi, int budget) > > > pkts = r_vec->tx_pkts; > > > bytes = r_vec->tx_bytes; > > > } while (u64_stats_fetch_retry(&r_vec->tx_sync, start)); > > > > > > dim_update_sample(r_vec->event_ctr, pkts, bytes, &dim_sample); > > > - net_dim(&r_vec->tx_dim, dim_sample); > > > + net_dim(&r_vec->tx_dim, &dim_sample); > > > } > > > > > > return pkts_polled; > > > } > > --- snip --- > > > > Hi Caleb. Looks like a fair enough update to me in general, but I am not an > > expert on 'dim'. For the corresponding nfp driver changes feel free to add: > > > > Signed-off-by: Louis Peens <louis.peens@xxxxxxxxxxxx> > > Hi Louis, > Thanks for the review. Did you mean "Reviewed-by"? If there was a > change you were suggesting, I missed it. Hi - sorry, I do still manage to mix up when to use signed-off-by and reviewed-by. I did not suggest any changes no, and since the main focus of the patch is not the nfp driver I can see in hindsight that Reviewed-by: may make more sense. So updated: Reviewed-by: Louis Peens <louis.peens@xxxxxxxxxxxx> > > Best, > Caleb
