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Tue, 27 Apr 2021 14:59:26 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 27 Apr 2021 14:59:26 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 25651) id C0F6CE028D; Tue, 27 Apr 2021 16:59:25 +0200 (CEST) From: Christian Borntraeger To: peterz@infradead.org Cc: bristot@redhat.com, bsegall@google.com, dietmar.eggemann@arm.com, greg@kroah.com, gregkh@linuxfoundation.org, joshdon@google.com, juri.lelli@redhat.com, linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk, mgorman@suse.de, mingo@kernel.org, rostedt@goodmis.org, valentin.schneider@arm.com, vincent.guittot@linaro.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, borntraeger@de.ibm.com Subject: Re: sched: Move SCHED_DEBUG sysctl to debugfs Date: Tue, 27 Apr 2021 16:59:25 +0200 Message-Id: <20210427145925.5246-1-borntraeger@de.ibm.com> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210412102001.287610138@infradead.org> References: <20210412102001.287610138@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: eKX2-Ma5Wve74Wy6SnaoNJ_DMaO9FzIX X-Proofpoint-ORIG-GUID: oKwvlBcQkWFx-YEwG_gOPg9dEDJ3vNAT X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-27_08:2021-04-27,2021-04-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 mlxlogscore=823 bulkscore=0 spamscore=0 mlxscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104270105 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter, I just realized that we moved away sysctl tunabled to debugfs in next. We have seen several cases where it was benefitial to set sched_migration_cost_ns to a lower value. For example with KVM I can easily get 50% more transactions with 50000 instead of 500000. Until now it was possible to use tuned or /etc/sysctl.conf to set these things permanently. Given that some people do not want to have debugfs mounted all the time I would consider this a regression. The sysctl tunable was always available. I am ok with the "informational" things being in debugfs, but not the tunables. So how do we proceed here? Christian