From owner-freebsd-hackers@freebsd.org Mon Jan 13 15:50:01 2020 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 724E71E08E5 for ; Mon, 13 Jan 2020 15:50:01 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47xJ203GWSz3ByS for ; Mon, 13 Jan 2020 15:50:00 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: by mail-wr1-x429.google.com with SMTP id t2so9128930wrr.1 for ; Mon, 13 Jan 2020 07:50:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=8TCbYDTSzeI+o/sbdIDN+WQm6yj2ptsT34gQIRTyefk=; b=F8r4CyDYCnQsDlXEGcWDZHQ3kOpSQ6Z+W+mphQtEU2HaWd3/rHrseQHUh0OconIQ25 U9MW/RQr0vVk65GWRGIntTL+rtnsYfKBtCUSCG3BccJS9zOjZNlMXhwRD00ty2WrQGp3 v4fklNGKKo+SAxm/UidTxeQi1aG7YfTI6amLVt+ZtzKEglA6qKSxDXgR5sjNtk+MzQWf 5IzcnmktwadnE86vKv1ubvWNrCIkD4ie4IBR0WS8NITb6wzGS8FEyPM4V5oxt2YtTcmd UnNqweRxTrwROHlqkttIXlAfKecCMl9mvz8DnWUWXrjfNRnrbG1m9t9WK7O9aRMHltKk 7PyA== X-Gm-Message-State: APjAAAVKs7nmd1F8/UyCct98wxNRXxbPPdUtFZZwH++QoNPIvtrpZBQ6 iBhD04/+SrDzyIy44sOBgVSQqkub X-Google-Smtp-Source: APXvYqxWPUdntMVDCUNLNazasgu+3ZPj8mT5wlgAazMPIkC/uH9eMIySGuv9bgOaAIjR7rL7v1le0w== X-Received: by 2002:a5d:538e:: with SMTP id d14mr19792848wrv.358.1578930598292; Mon, 13 Jan 2020 07:49:58 -0800 (PST) Received: from gumby.homeunix.com ([2.221.16.6]) by smtp.gmail.com with ESMTPSA id u22sm16534133wru.30.2020.01.13.07.49.55 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jan 2020 07:49:57 -0800 (PST) Date: Mon, 13 Jan 2020 15:49:52 +0000 From: RW To: freebsd-hackers@freebsd.org Subject: Re: adding some smartness in file cache Message-ID: <20200113154952.54bb4156@gumby.homeunix.com> In-Reply-To: References: X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; amd64-portbld-freebsd12.0) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 47xJ203GWSz3ByS X-Spamd-Bar: -- X-Spamd-Result: default: False [-3.00 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; FREEMAIL_FROM(0.00)[googlemail.com]; TO_DN_NONE(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[googlemail.com:+]; DMARC_POLICY_ALLOW(-0.50)[googlemail.com,quarantine]; RECEIVED_SPAMHAUS_PBL(0.00)[6.16.221.2.khpj7ygk5idzvmvt5x4ziurxhy.zen.dq.spamhaus.net : 127.0.0.10]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[googlemail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; DWL_DNSWL_NONE(0.00)[googlemail.com.dwl.dnswl.org : 127.0.5.0]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[googlemail.com:s=20161025]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; IP_SCORE(0.00)[ip: (-9.39), ipnet: 2a00:1450::/32(-2.60), asn: 15169(-1.84), country: US(-0.05)]; RCVD_IN_DNSWL_NONE(0.00)[9.2.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.5.4.1.0.0.a.2.list.dnswl.org : 127.0.5.0]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Jan 2020 15:50:01 -0000 On Mon, 13 Jan 2020 01:13:31 -0800 Conrad Meyer wrote: > Consider modifying your linear scan programs to use posix_fadvise(2) > POSIX_FADV_DONTNEED and/or POSIX_FADV_NOREUSE. > > You're right that we could be a bit more clever than straight LRU for > eviction (if we are not already), It may have changed, but the last I looked, the active queue was clever than straight LRU and that was governing the expiry of mmap file cache. There was a thread a few years ago where someone posted a contrived test that appeared to show Linux caching as more effective. However, the results were consistent with Linux evicting mmap cache LRU and FreeBSD retaining twice accessed pages over more recently accessed single access pages.