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Message-ID: <20221006003104.GA30279@fastly.com>
Date: Wed, 5 Oct 2022 17:31:05 -0700
From: Joe Damato <jdamato@...tly.com>
To: "Samudrala, Sridhar" <sridhar.samudrala@...el.com>
Cc: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
kuba@...nel.org, davem@...emloft.net, anthony.l.nguyen@...el.com,
jesse.brandeburg@...el.com, maciej.fijalkowski@...el.com
Subject: Re: [next-queue v2 2/4] i40e: Record number TXes cleaned during NAPI
On Wed, Oct 05, 2022 at 07:16:56PM -0500, Samudrala, Sridhar wrote:
> On 10/5/2022 4:21 PM, Joe Damato wrote:
> >Update i40e_clean_tx_irq to take an out parameter (tx_cleaned) which stores
> >the number TXs cleaned.
> >
> >Likewise, update i40e_clean_xdp_tx_irq and i40e_xmit_zc to do the same.
> >
> >Care has been taken to avoid changing the control flow of any functions
> >involved.
> >
> >Signed-off-by: Joe Damato <jdamato@...tly.com>
> >---
> > drivers/net/ethernet/intel/i40e/i40e_txrx.c | 16 +++++++++++-----
> > drivers/net/ethernet/intel/i40e/i40e_xsk.c | 15 +++++++++++----
> > drivers/net/ethernet/intel/i40e/i40e_xsk.h | 3 ++-
> > 3 files changed, 24 insertions(+), 10 deletions(-)
> >
> >diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> >index b97c95f..a2cc98e 100644
> >--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> >+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> >@@ -923,11 +923,13 @@ void i40e_detect_recover_hung(struct i40e_vsi *vsi)
> > * @vsi: the VSI we care about
> > * @tx_ring: Tx ring to clean
> > * @napi_budget: Used to determine if we are in netpoll
> >+ * @tx_cleaned: Out parameter set to the number of TXes cleaned
> > *
> > * Returns true if there's any budget left (e.g. the clean is finished)
> > **/
> > static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> >- struct i40e_ring *tx_ring, int napi_budget)
> >+ struct i40e_ring *tx_ring, int napi_budget,
> >+ unsigned int *tx_cleaned)
> > {
> > int i = tx_ring->next_to_clean;
> > struct i40e_tx_buffer *tx_buf;
> >@@ -1026,7 +1028,7 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> > i40e_arm_wb(tx_ring, vsi, budget);
> > if (ring_is_xdp(tx_ring))
> >- return !!budget;
> >+ goto out;
> > /* notify netdev of completed buffers */
> > netdev_tx_completed_queue(txring_txq(tx_ring),
> >@@ -1048,6 +1050,8 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> > }
> > }
> >+out:
> >+ *tx_cleaned = total_packets;
> > return !!budget;
> > }
> >@@ -2689,10 +2693,12 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
> > container_of(napi, struct i40e_q_vector, napi);
> > struct i40e_vsi *vsi = q_vector->vsi;
> > struct i40e_ring *ring;
> >+ bool tx_clean_complete = true;
> > bool clean_complete = true;
> > bool arm_wb = false;
> > int budget_per_ring;
> > int work_done = 0;
> >+ unsigned int tx_cleaned = 0;
> > if (test_bit(__I40E_VSI_DOWN, vsi->state)) {
> > napi_complete(napi);
> >@@ -2704,11 +2710,11 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
> > */
> > i40e_for_each_ring(ring, q_vector->tx) {
> > bool wd = ring->xsk_pool ?
> >- i40e_clean_xdp_tx_irq(vsi, ring) :
> >- i40e_clean_tx_irq(vsi, ring, budget);
> >+ i40e_clean_xdp_tx_irq(vsi, ring, &tx_cleaned) :
> >+ i40e_clean_tx_irq(vsi, ring, budget, &tx_cleaned);
> > if (!wd) {
> >- clean_complete = false;
> >+ clean_complete = tx_clean_complete = false;
> > continue;
> > }
> > arm_wb |= ring->arm_wb;
> >diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> >index 790aaeff..f98ce7e4 100644
> >--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> >+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> >@@ -530,18 +530,22 @@ static void i40e_set_rs_bit(struct i40e_ring *xdp_ring)
> > * i40e_xmit_zc - Performs zero-copy Tx AF_XDP
> > * @xdp_ring: XDP Tx ring
> > * @budget: NAPI budget
> >+ * @tx_cleaned: Out parameter of the TX packets processed
> > *
> > * Returns true if the work is finished.
> > **/
> >-static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget)
> >+static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget,
> >+ unsigned int *tx_cleaned)
> > {
> > struct xdp_desc *descs = xdp_ring->xsk_pool->tx_descs;
> > u32 nb_pkts, nb_processed = 0;
> > unsigned int total_bytes = 0;
> > nb_pkts = xsk_tx_peek_release_desc_batch(xdp_ring->xsk_pool, budget);
> >- if (!nb_pkts)
> >+ if (!nb_pkts) {
> >+ *tx_cleaned = 0;
> > return true;
> >+ }
> > if (xdp_ring->next_to_use + nb_pkts >= xdp_ring->count) {
> > nb_processed = xdp_ring->count - xdp_ring->next_to_use;
> >@@ -558,6 +562,7 @@ static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget)
> > i40e_update_tx_stats(xdp_ring, nb_pkts, total_bytes);
> >+ *tx_cleaned = nb_pkts;
>
> With XDP, I don't think we should count these as tx_cleaned packets. These are transmitted
> packets. The tx_cleaned would be the xsk_frames counter in i40e_clean_xdp_tx_irq
> May be we need 2 counters for xdp.
I think there's two issues you are describing, which are separate in my
mind.
1.) The name "tx_cleaned", and
2.) Whether nb_pkts is the right thing to write as the out param.
For #1: I'm OK to change the name if that's the blocker here; please
suggest a suitable alternative that you'll accept.
For #2: nb_pkts is, IMO, the right value to bubble up to the tracepoint because
nb_pkts affects clean_complete in i40e_napi_poll which in turn determines
whether or not polling mode is entered.
The purpose of the tracepoint is to determine when/why/how you are entering
polling mode, so if nb_pkts plays a role in that calculation, it's the
right number to output.
> > return nb_pkts < budget;
> > }
> >@@ -581,10 +586,12 @@ static void i40e_clean_xdp_tx_buffer(struct i40e_ring *tx_ring,
> > * i40e_clean_xdp_tx_irq - Completes AF_XDP entries, and cleans XDP entries
> > * @vsi: Current VSI
> > * @tx_ring: XDP Tx ring
> >+ * @tx_cleaned: out parameter of number of TXes cleaned
> > *
> > * Returns true if cleanup/tranmission is done.
> > **/
> >-bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring)
> >+bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring,
> >+ unsigned int *tx_cleaned)
> > {
> > struct xsk_buff_pool *bp = tx_ring->xsk_pool;
> > u32 i, completed_frames, xsk_frames = 0;
> >@@ -634,7 +641,7 @@ bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring)
> > if (xsk_uses_need_wakeup(tx_ring->xsk_pool))
> > xsk_set_tx_need_wakeup(tx_ring->xsk_pool);
> >- return i40e_xmit_zc(tx_ring, I40E_DESC_UNUSED(tx_ring));
> >+ return i40e_xmit_zc(tx_ring, I40E_DESC_UNUSED(tx_ring), tx_cleaned);
> > }
> > /**
> >diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.h b/drivers/net/ethernet/intel/i40e/i40e_xsk.h
> >index 821df24..396ed11 100644
> >--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.h
> >+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.h
> >@@ -30,7 +30,8 @@ int i40e_xsk_pool_setup(struct i40e_vsi *vsi, struct xsk_buff_pool *pool,
> > bool i40e_alloc_rx_buffers_zc(struct i40e_ring *rx_ring, u16 cleaned_count);
> > int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget);
> >-bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring);
> >+bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring,
> >+ unsigned int *tx_cleaned);
> > int i40e_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags);
> > int i40e_realloc_rx_bi_zc(struct i40e_vsi *vsi, bool zc);
> > void i40e_clear_rx_bi_zc(struct i40e_ring *rx_ring);
>
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