From: Lukas Wunner <lukas@wunner.de>
To: Changwoo Min <changwoo@igalia.com>
Cc: lukasz.luba@arm.com, rafael@kernel.org, len.brown@intel.com,
pavel@kernel.org, christian.loehle@arm.com, tj@kernel.org,
kernel-dev@igalia.com, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/11] PM: EM: Add the infrastructure for command processing.
Date: Mon, 2 Jun 2025 21:59:40 +0200 [thread overview]
Message-ID: <aD4CrOmIwhUI-pet@wunner.de> (raw)
In-Reply-To: <20250529001315.233492-5-changwoo@igalia.com>
On Thu, May 29, 2025 at 09:13:08AM +0900, Changwoo Min wrote:
> +static int em_genl_cmd_doit(struct sk_buff *skb, struct genl_info *info)
> +{
> + struct param p = { .attrs = info->attrs };
> + struct sk_buff *msg;
> + void *hdr;
> + int cmd = info->genlhdr->cmd;
> + int ret = -EMSGSIZE;
> +
> + msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
> + if (!msg)
> + return -ENOMEM;
Just a heads-up, I know everyone recommends NLMSG_GOODSIZE but in reality
it's not that great because netlink_trim() reallocates the skb and copies
the entire linear buffer if it determines that the skb is half-empty.
Performance suffers as a result. So it's actually better to calculate
the exact message length prior to allocation. See the SPDM commit
referenced in my previous e-mail. Another lesson I had to learn the
hard way. :(
Thanks,
Lukas
next prev parent reply other threads:[~2025-06-02 19:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-29 0:13 [PATCH 00/11] PM: EM: Add netlink support for the energy model Changwoo Min
2025-05-29 0:13 ` [PATCH 01/11] PM: EM: Add ENERGY_MODEL_NETLINK Kconfig Changwoo Min
2025-05-29 0:13 ` [PATCH 02/11] PM: EM: Add a skeleton code for netlink notification Changwoo Min
2025-06-02 19:53 ` Lukas Wunner
2025-06-03 6:01 ` Changwoo Min
2025-05-29 0:13 ` [PATCH 03/11] PM: EM: Initialize the netlink notification during booting Changwoo Min
2025-05-29 0:13 ` [PATCH 04/11] PM: EM: Add the infrastructure for command processing Changwoo Min
2025-06-02 19:59 ` Lukas Wunner [this message]
2025-06-04 16:11 ` Changwoo Min
2025-05-29 0:13 ` [PATCH 05/11] PM: EM: Assign a unique ID when creating a performance domain Changwoo Min
2025-05-29 0:13 ` [PATCH 06/11] PM: EM: Expose the ID of a performance domain via debugfs Changwoo Min
2025-05-29 0:13 ` [PATCH 07/11] PM: EM: Add an iterator and accessor for the performance domain Changwoo Min
2025-05-29 0:13 ` [PATCH 08/11] PM: EM: Implement EM_GENL_CMD_PD_GET_ID Changwoo Min
2025-05-29 0:13 ` [PATCH 09/11] PM: EM: Implement EM_GENL_CMD_PD_GET_TBL Changwoo Min
2025-05-29 0:13 ` [PATCH 10/11] PM: EM: Implement event notification Changwoo Min
2025-05-29 0:13 ` [PATCH 11/11] PM: EM: Notify an event when the performance domain changes Changwoo Min
2025-06-02 11:52 ` [PATCH 00/11] PM: EM: Add netlink support for the energy model Lukasz Luba
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