From owner-freebsd-hackers@freebsd.org Fri Oct 16 10:15:56 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 85F3642FB4C for ; Fri, 16 Oct 2020 10:15:56 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (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 did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4CCMVg390gz4jwV for ; Fri, 16 Oct 2020 10:15:54 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 09GAFmKE017792 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 16 Oct 2020 13:15:51 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 09GAFmKE017792 Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 09GAFmjx017791; Fri, 16 Oct 2020 13:15:48 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 16 Oct 2020 13:15:48 +0300 From: Konstantin Belousov To: SHAMANTHA KRISHNA K G Cc: freebsd-hackers@freebsd.org Subject: Re: How to tune the number of pages that is brought into the memory when a page fault occurs . Message-ID: <20201016101548.GT2643@kib.kiev.ua> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on tom.home X-Rspamd-Queue-Id: 4CCMVg390gz4jwV X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=gmail.com (policy=none); spf=softfail (mx1.freebsd.org: 2001:470:d5e7:1::1 is neither permitted nor denied by domain of kostikbel@gmail.com) smtp.mailfrom=kostikbel@gmail.com X-Spamd-Result: default: False [0.05 / 15.00]; RCVD_TLS_ALL(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; NEURAL_SPAM_SHORT(0.12)[0.116]; MIME_GOOD(-0.10)[text/plain]; HAS_XAW(0.00)[]; NEURAL_HAM_MEDIUM(-0.07)[-0.073]; R_SPF_SOFTFAIL(0.00)[~all]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_SPAM_LONG(0.01)[0.005]; FREEMAIL_TO(0.00)[gmail.com]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; MAILMAN_DEST(0.00)[freebsd-hackers]; DMARC_POLICY_SOFTFAIL(0.10)[gmail.com : No valid SPF, No valid DKIM,none] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Oct 2020 10:15:56 -0000 On Fri, Oct 16, 2020 at 01:37:56PM +0530, SHAMANTHA KRISHNA K G wrote: > Hello All, > Is there any way of changing the number of pages that Is brought > into the memory when a page fault occurs? Look at madvise(2) and posix_madvise(2). It does not give the direct knob to change the number, but it allows to set a policy affecting this decision. In particular, it allows to disable prefeching at all with MADV_RANDOM. The mmap(2) syscall also provides MAP_PREFAULT_READ, read about it in the man page.