linux-kernel - Re: [PATCH] blk-rq-qos: Remove unlikely() hints from QoS checks

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Message-Id: <176775184768.14145.3891847681300037489.b4-ty@kernel.dk>
Date: Tue, 06 Jan 2026 19:10:47 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Breno Leitao <leitao@...ian.org>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
 tj@...nel.org, josef@...icpanda.com, kernel-team@...a.com
Subject: Re: [PATCH] blk-rq-qos: Remove unlikely() hints from QoS checks


On Tue, 06 Jan 2026 06:26:57 -0800, Breno Leitao wrote:
> The unlikely() annotations on QUEUE_FLAG_QOS_ENABLED checks are
> counterproductive. Writeback throttling (WBT) might be enabled by
> default, mainly because CONFIG_BLK_WBT_MQ defaults to 'y'.
> 
> Branch profiling on Meta servers, which have WBT enabled, confirms 100%
> misprediction rates on these checks.
> 
> [...]

Applied, thanks!

[1/1] blk-rq-qos: Remove unlikely() hints from QoS checks
      commit: 7d121d701d58a92f26decb10da1d04a88b74519d

Best regards,
-- 
Jens Axboe