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charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: AA25C100004 X-Stat-Signature: n7kc5n4m5y345dxfdew6tci8sfqnbttp X-Rspam-User: X-HE-Tag: 1679557876-961415 X-HE-Meta: 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 f9ETRc1x DWujgpBXWyWATyK3K6qMA8CKzTqGtFhoCgmRN0umvkV0ZOi3k0aFH/NExD3yzCQAUu/Bsh2c54KmzTSnGxQ10OQ4ab3Jmy8O+HxaIWdLtvy/M/cp2/z0e2MAufD4ZxwXvUfDASwW3uPmnTolINMiWK/gOdIzLeH7SrvREYA7wd4eSCsg= 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: On Wed 22-03-23 11:20:55, Marcelo Tosatti wrote: > On Wed, Mar 22, 2023 at 02:35:20PM +0100, Michal Hocko wrote: [...] > > > "Performance details for the kworker interruption: > > > > > > oslat 1094.456862: sys_mlock(start: 7f7ed0000b60, len: 1000) > > > oslat 1094.456971: workqueue_queue_work: ... function=vmstat_update ... > > > oslat 1094.456974: sched_switch: prev_comm=oslat ... ==> next_comm=kworker/5:1 ... > > > kworker 1094.456978: sched_switch: prev_comm=kworker/5:1 ==> next_comm=oslat ... > > > > > > The example above shows an additional 7us for the > > > > > > oslat -> kworker -> oslat > > > > > > switches. In the case of a virtualized CPU, and the vmstat_update > > > interruption in the host (of a qemu-kvm vcpu), the latency penalty > > > observed in the guest is higher than 50us, violating the acceptable > > > latency threshold for certain applications." > > > > Yes, I have seen that but it doesn't really give a wider context to > > understand why those numbers matter. > > OK. > > "In the case of RAN, a MAC scheduler with TTI=1ms, this causes >100us > interruption observed in a guest (which is above the safety > threshold for this application)." > > Is that OK? This might be a sufficient information for somebody familiar with the matter (not me). So no, not enough. We need to hear a more complete story. -- Michal Hocko SUSE Labs