From: Peter Zijlstra <peterz@infradead.org>
To: Cristian Prundeanu <cpru@amazon.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>,
Hazem Mohamed Abuelfotoh <abuehaze@amazon.com>,
Ali Saidi <alisaidi@amazon.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Geoff Blake <blakgeof@amazon.com>,
Csaba Csoma <csabac@amazon.com>,
Bjoern Doebel <doebel@amazon.com>,
Gautham Shenoy <gautham.shenoy@amd.com>,
Joseph Salisbury <joseph.salisbury@oracle.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Borislav Petkov <bp@alien8.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH v2] [tip: sched/core] sched: Move PLACE_LAG and RUN_TO_PARITY to sysctl
Date: Wed, 12 Feb 2025 10:17:11 +0100 [thread overview]
Message-ID: <20250212091711.GA19118@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250212053644.14787-1-cpru@amazon.com>
On Tue, Feb 11, 2025 at 11:36:44PM -0600, Cristian Prundeanu wrote:
> Replacing CFS with the EEVDF scheduler in kernel 6.6 introduced
> significant performance degradation in multiple database-oriented
> workloads. This degradation manifests in all kernel versions using EEVDF,
> across multiple Linux distributions, hardware architectures (x86_64,
> aarm64, amd64), and CPU generations.
>
> Testing combinations of available scheduler features showed that the
> largest improvement (short of disabling all EEVDF features) came from
> disabling both PLACE_LAG and RUN_TO_PARITY.
>
> Moving PLACE_LAG and RUN_TO_PARITY to sysctl will allow users to override
> their default values and persist them with established mechanisms.
Nope -- you have knobs in debugfs, and that's where they'll stay. Esp.
PLACE_LAG is super dodgy and should not get elevated to anything
remotely official.
Also, FYI, by keeping these emails threaded in the old thread I nearly
missed them again. I'm not sure where this nonsense of keeping
everything in one thread came from, but it is bloody stupid.
next prev parent reply other threads:[~2025-02-12 9:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-19 11:04 [GIT PULL] sched/urgent for v6.13 Borislav Petkov
2025-01-19 17:54 ` pr-tracker-bot
2025-01-28 23:09 ` [PATCH 0/2] [tip: sched/core] sched: Disable PLACE_LAG and RUN_TO_PARITY and move them to sysctl Cristian Prundeanu
2025-02-11 3:27 ` K Prateek Nayak
2025-02-12 5:41 ` Cristian Prundeanu
2025-02-12 9:43 ` Peter Zijlstra
2025-02-12 5:36 ` [PATCH v2] [tip: sched/core] sched: Move PLACE_LAG and RUN_TO_PARITY " Cristian Prundeanu
2025-02-12 9:17 ` Peter Zijlstra [this message]
2025-02-12 9:37 ` Peter Zijlstra
2025-02-12 23:00 ` Cristian Prundeanu
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