Re: [RFC PATCH 0/2] Introduce per-task io utilization boost

From: Christian Loehle <christian.loehle@arm.com>
To: Bart Van Assche <bvanassche@acm.org>, Qais Yousef <qyousef@layalina.io>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	juri.lelli@redhat.com, mingo@redhat.com, rafael@kernel.org,
	dietmar.eggemann@arm.com, vschneid@redhat.com,
	vincent.guittot@linaro.org, Johannes.Thumshirn@wdc.com,
	adrian.hunter@intel.com, ulf.hansson@linaro.org,
	andres@anarazel.de, asml.silence@gmail.com,
	linux-pm@vger.kernel.org, linux-block@vger.kernel.org,
	io-uring@vger.kernel.org, linux-mmc@vger.kernel.org
Subject: Re: [RFC PATCH 0/2] Introduce per-task io utilization boost
Date: Mon, 25 Mar 2024 12:06:16 +0000	[thread overview]
Message-ID: <de1eba3c-2453-4c5c-bd80-dd7d7b33f60d@arm.com> (raw)
In-Reply-To: <2ed2dadc-bdc4-4a21-8aca-a2aac0c6479a@acm.org>

On 21/03/2024 19:52, Bart Van Assche wrote:
> On 3/21/24 10:57, Christian Loehle wrote:
>> In the long-term it looks like for UFS the problem will disappear as we are
>> expected to get one queue/hardirq per CPU (as Bart mentioned), on NVMe that
>> is already the case.
> 
> Why the focus on storage controllers with a single completion interrupt?
> It probably won't take long (one year?) until all new high-end
> smartphones may have support for multiple completion interrupts.
> 
> Thanks,
> 
> Bart.
> 

Apart from going to "This patch shows significant performance improvements on
hardware that runs mainline today" to "This patch will have significant
performance improvements on devices running mainline in a couple years"
nothing in particular.
I'm fine with leaving it with having acknowledged the problem.
Maybe I would just gate the task placement on the task having been in
UFS (with multiple completion interrupts) or NVMe submission recently to
avoid regressions to current behavior in future versions. I did have that
already at some point, although it was a bit hacky.
Anyway, thank you for your input on that, it is what I wanted to hear!

Kind Regards,
Christian