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Date: Tue, 8 Sep 2020 07:38:38 +0200 From: Björn Töpel <bjorn.topel@...el.com> To: Jakub Kicinski <kuba@...nel.org>, Björn Töpel <bjorn.topel@...il.com> Cc: ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org, bpf@...r.kernel.org, magnus.karlsson@...el.com, intel-wired-lan@...ts.osuosl.org Subject: Re: [PATCH bpf-next 4/4] ixgbe, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget On 2020-09-07 21:32, Jakub Kicinski wrote: > On Mon, 7 Sep 2020 17:02:17 +0200 Björn Töpel wrote: >> From: Björn Töpel <bjorn.topel@...el.com> >> >> Start using XSK_NAPI_WEIGHT as NAPI poll budget for the AF_XDP Rx >> zero-copy path. >> >> Signed-off-by: Björn Töpel <bjorn.topel@...el.com> >> --- >> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c >> index 3771857cf887..f32c1ba0d237 100644 >> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c >> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c >> @@ -239,7 +239,7 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector, >> bool failure = false; >> struct sk_buff *skb; >> >> - while (likely(total_rx_packets < budget)) { >> + while (likely(total_rx_packets < XSK_NAPI_WEIGHT)) { > > I was thinking that we'd multiply 'budget' here, not replace it with a > constant. Looks like ixgbe dutifully passes 'per_ring_budget' into the > clean_rx functions, not a complete NAPI budget. > Correct, and i40e/ice does the same ("per_ring_budget"). As for budget << XSK_NAPI_MULT vs replacing; Replacing the budget is more in line with what the drivers do for the Tx cleanup (xxx_clean_tx_irq), where the napi budget is discarded completely; Again, with the idea that "this is much cheaper than a "per-packet through the stack". Do you prefer the multiplier way that you describe? Cheers, Björn >> union ixgbe_adv_rx_desc *rx_desc; >> struct ixgbe_rx_buffer *bi; >> unsigned int size; >
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