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x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4F71A1C000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: p4rf7bm9mxzin75y16bjaik4eaqbyhry X-HE-Tag: 1699456556-957379 X-HE-Meta: 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 TjAFrH0E H38OStFEc5AkqMh76bHFRQqBwkjTSNV69Mmto9dHVbtEICJ/v6tUBQnuV/WrlwGFcmWAdDd2gihEY+kbzbbF992iY48GV3BBi+CgGM2Si9RYgCFBlwu1wk4BQd0uocby3otj+CDjv0wyD5hgmL8ajstRXSxyT/WknqxR4oTd8UyYezEWkM7XF3qSvi+BQ9r+A8fJm260Bh0/+BpziyOmWI7SF/QtgqS80lzVc5Hwm/FIFlDlK4ic9IJB7wz7w8cwEV3SRZx9yQrtHE7wSGSSRIioaMy8xv2FUwWNIjROIUCAIRxSB+xcqqLQayE0Ut8XkuQjQeVV95PGlmGPmvPjC39gOi3bGFghRhNzK X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 8 Nov 2023 09:43:10 +0000 David Laight wrote: > > Policies: > > > > A - preemption=none: run to completion > > B - preemption=voluntary: run to completion, unless a task of higher > > sched-class awaits > > C - preemption=full: optimized for low-latency. Preempt whenever a higher > > priority task awaits. > > If you remove cond_resched() then won't both B and C require an extra IPI. > That is probably OK for RT tasks but could get expensive for > normal tasks that aren't bound to a specific cpu. What IPI is extra? > > I suspect C could also lead to tasks being pre-empted just before > they sleep (eg after waking another task). > There might already be mitigation for that, I'm not sure if > a voluntary sleep can be done in a non-pre-emptible section. No, voluntary sleep can not be done in a preemptible section. -- Steve