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Date: Mon, 12 May 2014 06:57:08 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: Amir Vadai <amirv@...lanox.com> Cc: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org, Yevgeny Petrilin <yevgenyp@...lanox.com>, Or Gerlitz <ogerlitz@...lanox.com>, Yuval Atias <yuvala@...lanox.com> Subject: Re: [PATCH net-next 1/9] net/mlx4_core: Enforce irq affinity changes immediatly On Mon, 2014-05-12 at 10:43 +0300, Amir Vadai wrote: > From: Yuval Atias <yuvala@...lanox.com> > > During heavy traffic, napi is constatntly polling the complition queue > and no interrupt is fired. Because of that, changes to irq affinity are > ignored until traffic is stopped and resumed. > > By registering to the irq notifier mechanism, and forcing interrupt when > affinity is changed, irq affinity changes will be immediatly enforced. > > Signed-off-by: Yuval Atias <yuvala@...lanox.com> > Signed-off-by: Amir Vadai <amirv@...lanox.com> > --- Interesting. Its a bit sad it has to be in fast path... > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c > index 89585c6..81b7571 100644 > --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c > @@ -474,9 +474,15 @@ int mlx4_en_poll_tx_cq(struct napi_struct *napi, int budget) > /* If we used up all the quota - we're probably not done yet... */ > if (done < budget) { > /* Done for now */ > + cq->mcq.irq_affinity_change = 0; > napi_complete(napi); > mlx4_en_arm_cq(priv, cq); > return done; > + } else if (unlikely(cq->mcq.irq_affinity_change)) { > + cq->mcq.irq_affinity_change = 0; > + napi_complete(napi); > + mlx4_en_arm_cq(priv, cq); > + return 0; > } > return budget; > priv->msix_ctl.pool_bm &= ~(1ULL << i); > diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h > index ba87bd2..74f5aa8 100644 > --- a/include/linux/mlx4/device.h > +++ b/include/linux/mlx4/device.h > @@ -586,6 +586,8 @@ struct mlx4_cq { > > atomic_t refcount; > struct completion free; > + u16 irq; > + bool irq_affinity_change; > }; > > struct mlx4_qp { But could you place irq_affinity_change in another cache line ? It seems there is a 32bit hole between cons_index and set_ci_db (Both fields can be moved) Thanks -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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