From nobody Tue Jun 8 09:26:45 2021 X-Original-To: freebsd-stable@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 527517EC0F1 for ; Tue, 8 Jun 2021 09:26:49 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FzlHY1wjlz3mYc; Tue, 8 Jun 2021 09:26:49 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from [192.168.0.88] (unknown [195.64.148.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: avg/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 942AA5BD0; Tue, 8 Jun 2021 09:26:48 +0000 (UTC) (envelope-from avg@FreeBSD.org) Subject: Re: Where might memory be reported? To: Chris , Dewayne Geraghty Cc: Dave Hayes , freebsd-stable@freebsd.org References: <20210606160913.167e6c0a@bigus.dream-tech.com> <20210607115334.6e9d1178@bigus.dream-tech.com> <6c174c830019d133fbb4daefe442fb40@bsdforge.com> <7a70082c6e7e8f948e5c6f92c70174fc@bsdforge.com> From: Andriy Gapon Message-ID: Date: Tue, 8 Jun 2021 12:26:45 +0300 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.11.0 List-Id: Production branch of FreeBSD source code List-Archive: https://lists.freebsd.org/archives/freebsd-stable List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-stable@freebsd.org X-BeenThere: freebsd-stable@freebsd.org MIME-Version: 1.0 In-Reply-To: <7a70082c6e7e8f948e5c6f92c70174fc@bsdforge.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam: Yes X-ThisMailContainsUnwantedMimeParts: N On 08/06/2021 10:39, Chris wrote: > On 2021-06-07 22:58, Dewayne Geraghty wrote: >> This issue was raised in April '21 by Andriy Gapon title "stable/13, vm >> page counts do not add up". >> >> This was mentioned >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253281 >> though its probably more of an affirmation of a symptom. (reminder to >> adjust status) >> >> More relevant is >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234559 >> where Mark Johnson advised (in Feb '19) >> "I've thought about this some more and decided to close this bug WONTFIX >> for now.  Basically, we started lazily dequeuing wired pages to avoid >> the page queue synchronization cost incurred by frequent wirings.  The >> result is that wired pages may temporarily be counted as >> active/inactive/laundry despite not being reclaimable.  Maintaining the >> previous behaviour wrt statistics would introduce synchronization >> overhead that we've been trying to avoid in past and future work.  I >> don't plan to change the current behaviour and there doesn't seem to be >> a compelling reason to do so, at least based on this report.  If you or >> anyone else would like to discuss this further or describe a use-case >> that depends on the old behaviour, please feel free to re-open the bug." > tl;dr > I recognize this needs work. But it's a GREAT DEAL of work, and I currently > have much shinier things on my to-do list. ;-) > > No offense to Mark. He's doing a tremendous job. I just couldn't resist. :-) Just to clarify, Mark was commenting on small discrepancies (deviations, fluctuations) that can happen because of lazy statistics. The large and persistent (and growing) mismatch seems like a different problem. -- Andriy Gapon