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[174.88.77.103]) by smtp.gmail.com with ESMTPSA id g19sm1344886qka.84.2020.10.07.06.30.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 06:30:43 -0700 (PDT) Sender: Mark Johnston Date: Wed, 7 Oct 2020 09:30:39 -0400 From: Mark Johnston To: SHAMANTHA KRISHNA K G Cc: freebsd-hackers@freebsd.org Subject: Re: swap vm object Message-ID: <20201007122452.GA92185@raichu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4C5wFd4bhnz4px7 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=ER5o/ngf; dmarc=none; spf=pass (mx1.freebsd.org: domain of markjdb@gmail.com designates 2607:f8b0:4864:20::734 as permitted sender) smtp.mailfrom=markjdb@gmail.com X-Spamd-Result: default: False [-2.07 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_HAM_SHORT(-0.31)[-0.315]; FREEMAIL_TO(0.00)[gmail.com]; FORGED_SENDER(0.30)[markj@freebsd.org,markjdb@gmail.com]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; FROM_NEQ_ENVFROM(0.00)[markj@freebsd.org,markjdb@gmail.com]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.02)[-1.020]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; NEURAL_HAM_LONG(-1.04)[-1.036]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; DMARC_NA(0.00)[freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::734:from]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[freebsd-hackers] 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: Wed, 07 Oct 2020 13:30:51 -0000 On Wed, Oct 07, 2020 at 01:28:34PM +0530, SHAMANTHA KRISHNA K G wrote: > Hello All , > > What is a swap vm object in case of /proc//map ? It represents memory that is backed by the swap device. If the system is forced to reclaim memory from this object, it will first use the swap pager to write the pages' contents to a swap device. Then, a subsequent access can recover the data by paging in from the swap device. Often such objects contain anonymous pages, such as those allocated using malloc(). They are also used for certain persistent objects, such as tmpfs or shared memory files.