linux-kernel - Re: [RFT][PATCH v1 0/5] cpuidle: menu: Avoid discarding useful information when processing recent idle intervals

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Message-ID: <CAJZ5v0jUM6TKJuJsA9ZJF1PvnudOmJFd0RC26iQd0zQSWM+wnA@mail.gmail.com>
Date: Fri, 7 Feb 2025 16:35:50 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Christian Loehle <christian.loehle@....com>
Cc: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>, 
	"Rafael J. Wysocki" <rjw@...ysocki.net>, Linux PM <linux-pm@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	Aboorva Devarajan <aboorvad@...ux.ibm.com>
Subject: Re: [RFT][PATCH v1 0/5] cpuidle: menu: Avoid discarding useful
 information when processing recent idle intervals

On Fri, Feb 7, 2025 at 4:24 PM Christian Loehle
<christian.loehle@....com> wrote:
>
> On 2/7/25 14:48, Artem Bityutskiy wrote:
> > Hi,
> >
> > thanks for the patches!
> >
> > On Thu, 2025-02-06 at 15:21 +0100, Rafael J. Wysocki wrote:
> >> Hi Everyone,
> >>
> >> This work had been triggered by a report that commit 0611a640e60a ("eventpoll:
> >> prefer kfree_rcu() in __ep_remove()") had caused the critical-jOPS metric of
> >> the SPECjbb 2015 benchmark [1] to drop by around 50% even though it generally
> >> reduced kernel overhead.  Indeed, it was found during further investigation
> >> that the total interrupt rate while running the SPECjbb workload had fallen as
> >> a result of that commit by 55% and the local timer interrupt rate had fallen
> >> by
> >> almost 80%.
> >
> > I ran SPECjbb2015 with and it doubles critical-jOPS and basically makes it
> > "normal" again. Thanks!
> >
> > Reported-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
> > Tested-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
> >
>
> I'll go take a look in-depth, honestly the statistical test of
> get_typical_interval() is somewhat black magic to me before and after
> 4/5, so if that actually works better fine with me.
> I'll run some tests, too.

Thank you!