From: "Eliot Courtney" <ecourtney@nvidia.com>
To: "Alexandre Courbot" <acourbot@nvidia.com>,
"Danilo Krummrich" <dakr@kernel.org>,
"Alice Ryhl" <aliceryhl@google.com>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>
Cc: "John Hubbard" <jhubbard@nvidia.com>,
"Alistair Popple" <apopple@nvidia.com>,
"Timur Tabi" <ttabi@nvidia.com>,
"Eliot Courtney" <ecourtney@nvidia.com>,
"Zhi Wang" <zhiw@nvidia.com>, <nova-gpu@lists.linux.dev>,
<linux-kernel@vger.kernel.org>, <rust-for-linux@vger.kernel.org>
Subject: Re: [PATCH v2] gpu: nova-core: gsp: cmdq: reduce sleep delta in wait_for_msg
Date: Mon, 02 Nov 2026 21:38:54 +0900 [thread overview]
Message-ID: <DMKQC4Q6U4RM.21P0QP6K5ORUQ@nvidia.com> (raw)
In-Reply-To: <20261102-cmdq_wait_msg_timeout-v2-1-50bc4534b659@nvidia.com>
On Mon Nov 2, 2026 at 9:30 PM JST, Alexandre Courbot wrote:
> If a message is not immediately available on the queue, `wait_for_msg`
> sleeps for 1 millisecond before checking again. This is 3 orders of
> magnitude more than Nouveau (which sleeps for 1 microsecond) or OpenRM
> (which does not sleep at all and busy-polls) and is way too much, as GSP
> commands are expected to be processed much faster than that.
>
> Reduce the sleep time to 1 microsecond. This effectively makes `fsleep`
> busy-loop with a call to `cpu_relax` afterwards, keeping latency to a
> minimum.
>
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
> Changes in v2:
> - Wait for 1 microsecond. (Eliot)
> - Link to v1: https://patch.msgid.link/20261030-cmdq_wait_msg_timeout-v1-1-a1e628d2732c@nvidia.com
> ---
Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
next prev parent reply other threads:[~2026-11-02 12:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 12:30 [PATCH v2] gpu: nova-core: gsp: cmdq: reduce sleep delta in wait_for_msg Alexandre Courbot
2026-11-02 12:38 ` Eliot Courtney [this message]
2026-11-02 12:39 ` Danilo Krummrich
2026-11-02 14:00 ` Alexandre Courbot
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