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Tue, 10 Jan 2023 09:05:56 -0500 X-MC-Unique: 6KuOp-ugNeuH5PpnU3dh4g-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 31C121C0040E; Tue, 10 Jan 2023 14:05:56 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B931E492C14; Tue, 10 Jan 2023 14:05:55 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 44EDF4052FE9B; Tue, 10 Jan 2023 08:50:28 -0300 (-03) Date: Tue, 10 Jan 2023 08:50:28 -0300 From: Marcelo Tosatti To: Hillf Danton Cc: atomlin@atomlin.com, frederic@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full Message-ID: References: <20230105125218.031928326@redhat.com> <20230106001244.4463-1-hdanton@sina.com> <20230106150154.4560-1-hdanton@sina.com> <20230107001529.4617-1-hdanton@sina.com> <20230110024356.336-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230110024356.336-1-hdanton@sina.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A50DD4002D X-Rspam-User: X-Stat-Signature: aondkxf17po1nhtt816h19ypmietk4n1 X-HE-Tag: 1673359558-129115 X-HE-Meta: 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 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 Tue, Jan 10, 2023 at 10:43:56AM +0800, Hillf Danton wrote: > On 9 Jan 2023 11:12:49 -0300 Marcelo Tosatti > > > > Yes, but if you do not return to userspace, then the per-CPU vm > > statistics can be dirty indefinitely. > > Could you specify the reasons for failing to return to userspace, > given it is undesired intereference for the shepherd to queue work > on the isolated CPUs. Any system call that takes longer than the threshold to sync vmstats. Or a long running kernel thread, for example: https://stackoverflow.com/questions/65111483/long-running-kthread-and-synchronize-net