linux-kernel - Re: [PATCH net-next v4] mlx5/core: Schedule EQ comp tasklet only if necessary

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Message-ID: <20241111141321.0d723c9d@kernel.org>
Date: Mon, 11 Nov 2024 14:13:21 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Caleb Sander Mateos <csander@...estorage.com>
Cc: Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>,
 Tariq Toukan <tariqt@...dia.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Parav Pandit
 <parav@...dia.com>, netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v4] mlx5/core: Schedule EQ comp tasklet only if
 necessary

On Tue,  5 Nov 2024 13:39:59 -0700 Caleb Sander Mateos wrote:
> Currently, the mlx5_eq_comp_int() interrupt handler schedules a tasklet
> to call mlx5_cq_tasklet_cb() if it processes any completions. For CQs
> whose completions don't need to be processed in tasklet context, this
> adds unnecessary overhead. In a heavy TCP workload, we see 4% of CPU
> time spent on the tasklet_trylock() in tasklet_action_common(), with a
> smaller amount spent on the atomic operations in tasklet_schedule(),
> tasklet_clear_sched(), and locking the spinlock in mlx5_cq_tasklet_cb().
> TCP completions are handled by mlx5e_completion_event(), which schedules
> NAPI to poll the queue, so they don't need tasklet processing.

Applied, thanks